Trinity

The Christian doctrine of the Trinity defines God as three divine persons or hypostases: the Father, the Son (Jesus Christ), and the Holy Spirit; "one God in three persons". The three persons are distinct, yet are one "substance, essence or nature". A nature is what one is, while a person is who one is.

The Trinity is considered to be a mystery of Christian faith. According to this doctrine, there is only one God in three persons. Each person is God, whole and entire. They are distinct from one another in their relations of origin: as the Fourth Lateran Council declared, "it is the Father who generates, the Son who is begotten, and the Holy Spirit who proceeds". While distinct in their relations with one another, they are one in all else. The whole work of creation and grace is a single operation common to all three divine persons, who at the same time operate according to their unique properties, so that all things are from the Father, through the Son and in the Holy Spirit. The three persons are co-equal, co-eternal and consubstantial.

Trinitarianism (one deity in three persons) contrasts with nontrinitarian positions which include Binitarianism (one deity in two persons, or two deities), Unitarianism (one deity in one person, analogous to Jewish interpretation of the Shema and Muslim belief in Tawhid), Oneness Pentecostalism or Modalism (one deity manifested in three separate aspects), and social trinitarianism (three persons united by mutual love and accord).

Etymology

The English word "Trinity" is derived from Latin "Trinitas", meaning "the number three, a triad". This abstract noun is formed from the adjective "trinus" (three each, threefold, triple), as the word "unitas" is the abstract noun formed from "unus" (one).

The corresponding word in Greek is "Τριάς", meaning "a set of three" or "the number three".

The first recorded use of this Greek word in Christian theology (though not about the Divine Trinity) was by Theophilus of Antioch in about 170. He wrote:

In like manner also the three days which were before the luminaries, are types of the Trinity [Τριάδος], of God, and His Word, and His wisdom. And the fourth is the type of man, who needs light, that so there may be God, the Word, wisdom, man.

Tertullian, a Latin theologian who wrote in the early 3rd century, is credited as being the first to use the Latin words "Trinity", "person" and "substance" to explain that the Father, Son, and Holy Spirit are "one in essence—not one in Person".

History

The Ante-Nicene Fathers affirmed Christ's deity and spoke of "Father, Son and Holy Spirit", even though their language is not that of the traditional doctrine as formalised in the fourth century. Trinitarians view these as elements of the codified doctrine. Ignatius of Antioch provides early support for the Trinity around 110, exhorting obedience to "Christ, and to the Father, and to the Spirit". Justin Martyr (AD 100–c. 165) also writes, "in the name of God, the Father and Lord of the universe, and of our Saviour Jesus Christ, and of the Holy Spirit". The first of the early church fathers to be recorded using the word "Trinity" was Theophilus of Antioch writing in the late 2nd century. He defines the Trinity as God, His Word (Logos) and His Wisdom (Sophia) in the context of a discussion of the first three days of creation. The first defence of the doctrine of the Trinity was in the early 3rd century by the early church father Tertullian. He explicitly defined the Trinity as Father, Son, and Holy Spirit and defended the Trinitarian theology against the "Praxean" heresy.

Although there is much debate as to whether the beliefs of the Apostles were merely articulated and explained in the Trinitarian Creeds, or were corrupted and replaced with new beliefs, all scholars recognize that the Creeds themselves were created in reaction to disagreements over the nature of the Father, Son, and Holy Spirit. These controversies, however, were great and many, and took some centuries to be resolved.

Of these controversies, the most significant developments were articulated in the first four centuries by the Church Fathers in reaction to Adoptionism, Sabellianism, and Arianism. Adoptionism was the belief that Jesus was an ordinary man, born of Joseph and Mary, who became the Christ and Son of God at his baptism. In 269, the Synods of Antioch condemned Paul of Samosata for his Adoptionist theology, and also condemned the term homoousios (ὁμοούσιος, "of the same being") in the sense he used it.

Sabellianism taught that the Father, the Son, and the Holy Spirit are essentially one and the same, the difference being simply verbal, describing different aspects or roles of a single being. For this view Sabellius was excommunicated for heresy in Rome c. 220.

In the fourth century, Arianism, as traditionally understood, taught that the Father existed prior to Son who was not, by nature, God but rather a changeable creature who was granted the dignity of becoming "Son of God". In 325, the Council of Nicaea adopted the Nicene Creed which described Christ as "God of God, Light of Light, very God of very God, begotten, not made, being of one substance with the Father". The creed used the term homoousios (of one substance) to define the relationship between the Father and the Son. After more than fifty years of debate, homoousios was recognised as the hallmark of orthodoxy, and was further developed into the formula of "three persons, one being".

Athanasius, who was present at the Council as one of the Bishop of Alexandria's assistants, stated that the bishops were forced to use this terminology, which is not found in Scripture, because the biblical phrases that they would have preferred to use were claimed by the Arians to be capable of being interpreted in what the bishops considered to be a heretical sense. Moreover, the meanings of "ousia" and " hypostasis" overlapped then, so that "hypostasis" for some meant "essence" and for others "person". Athanasius of Alexandria (293–373) helped to separate the terms.

The Confession of the Council of Nicaea said little about the Holy Spirit. The doctrine of the divinity and personality of the Holy Spirit was developed by Athanasius in the last decades of his life. He defended and refined the Nicene formula. By the end of the 4th century, under the leadership of Basil of Caesarea, Gregory of Nyssa, and Gregory of Nazianzus (the Cappadocian Fathers), the doctrine had reached substantially its current form.

Theology

Trinitarian baptismal formula

In the synoptic Gospels the baptism of Jesus is often interpreted as a manifestation of all three persons of the Trinity: "And when Jesus was baptized, he went up immediately from the water, and behold, the heavens were opened and he saw the spirit of God descending like a dove, and alighting on him; and lo, a voice from heaven, saying, 'This is my beloved Son, with whom I am well pleased.'"^{[ Mt 3:16–17]} Baptism is generally conferred with the Trinitarian formula, "in the name of the Father, and of the Son, and of the Holy Spirit".^{[ Mt 28:19]} Trinitarians identify this name with the Christian faith into which baptism is an initiation, as seen for example in the statement of Basil the Great (330–379): "We are bound to be baptized in the terms we have received, and to profess faith in the terms in which we have been baptized." The First Council of Constantinople (381) also says, "This is the Faith of our baptism that teaches us to believe in the Name of the Father, of the Son and of the Holy Spirit. According to this Faith there is one Godhead, Power, and Being of the Father, of the Son, and of the Holy Spirit." Matthew 28:19 may be taken to indicate that baptism was associated with this formula from the earliest decades of the Church's existence.

Nontrinitarian groups, such as Oneness Pentecostals, demur from the Trinitarian view on baptism. For them, the omission of the formula in Acts outweighs all other considerations, and is a liturgical guide for their own practice. For this reason, they often focus on the baptisms in Acts, citing many authoritative theological works. Those who place great emphasis on the baptisms in Acts often likewise question the authenticity of Matthew 28:19 in its present form. Most scholars of New Testament textual criticism accept the authenticity of the passage, since there are no variant manuscripts regarding the formula, and the extant form of the passage is attested in the Didache and other patristic works of the 1st and 2nd centuries: Ignatius, Tertullian, Hippolytus, Cyprian, and Gregory Thaumaturgus.

Commenting on Matthew 28:19, Gerhard Kittel states:

This threefold relation [of Father, Son and Spirit] soon found fixed expression in the triadic formulae in 2 Cor. 13:14 and in 1 Cor. 12:4–6. The form is first found in the baptismal formula in Matthew 28:19; Did., 7. 1 and 3....[I]t is self-evident that Father, Son and Spirit are here linked in an indissoluble threefold relationship.

One God

Christianity, having emerged from Judaism, is a monotheistic religion. Never in the New Testament does the trinitarian concept become a " tritheism" (three Gods) nor even two. God is one, and that the Godhead is a single being is strongly declared in the Bible:

• The Shema of the Hebrew Scriptures: "Hear, O Israel: the LORD our God, the LORD is one."^{[ Deut 6:4]}
• The first of the Ten Commandments—"Thou shalt have no other gods before me."^{[ 5:7]}
• And "Thus saith the LORD the King of Israel and his redeemer the LORD of hosts: I am the first and I am the last; and beside me there is no God."^{[ Isa 44:6]}
• In the New Testament: "The Lord our God is one."^{[ Mk 12:29]}

In the Trinitarian view, the Father and the Son and the Holy Ghost share the one essence, substance or being. The central and crucial affirmation of Christian faith is that there is one savior, God, and one salvation, manifest in Jesus Christ, to which there is access only because of the Holy Spirit. The God of the Old Testament is still the same as the God of the New. In Christianity, statements about a single God are intended to distinguish the Hebraic understanding from the polytheistic view, which see divine power as shared by several beings, beings which can and do disagree and have conflicts with each other.

God in three persons

In Trinitarian doctrine, God exists as three persons or hypostases, but is one being, having a single divine nature. The members of the Trinity are co-equal and co-eternal, one in essence, nature, power, action, and will. As stated in the Athanasian Creed, the Father is uncreated, the Son is uncreated, and the Holy Spirit is uncreated, and all three are eternal with no beginning. "The Father and the Son and the Holy Spirit" are not names for different parts of God, but one name for God because three persons exist in God as one entity. They cannot be separate from one another. Each person is understood as having the identical essence or nature, not merely similar natures.

God has always loved, and there has always existed perfectly harmonious communion between the three persons of the Trinity. One consequence of this teaching is that God could not have created man to have someone to talk to or to love: God "already" enjoyed personal communion; being perfect, he did not create man because of a lack or inadequacy he had. Another consequence, according to Rev. Fr. Thomas Hopko, an Eastern Orthodox theologian, is that if God were not a Trinity, he could not have loved prior to creating other beings on whom to bestow his love. Thus God says, "Let us make man in our image, in our likeness, and let them rule over the fish of the sea and the birds of the air, over the livestock, over all the earth, and over all the creatures that move along the ground. So God created man in his own image, in the image of God he created him; male and female he created them."^{[ Gen 1:26–7]} For Trinitarians, emphasis in Genesis 1:26 is on the plurality in the Deity, and in 1:27 on the unity of the divine Essence. A possible interpretation of Genesis 1:26 is that God's relationships in the Trinity are mirrored in man by the ideal relationship between husband and wife, two persons becoming one flesh, as described in Eve's creation later in the next chapter.^{[ 2:22]}

Perichoresis

Perichoresis from Greek ("going around", "envelopment") is a term used by some theologians to describe the relationship between the members of the Trinity. The Latin equivalent for this term is circumincessio. This concept refers for its basis to John 14–17, where Jesus is instructing the disciples concerning the meaning of his departure. His going to the Father, he says, is for their sake; so that he might come to them when the "other comforter" is given to them. Then, he says, his disciples will dwell in him, as he dwells in the Father, and the Father dwells in him, and the Father will dwell in them. This is so, according to the theory of perichoresis, because the persons of the Trinity "reciprocally contain one another, so that one permanently envelopes and is permanently enveloped by, the other whom he yet envelopes". ( Hilary of Poitiers, Concerning the Trinity 3:1).

Perichoresis effectively excludes the idea that God has parts, but rather is a simple being. It also harmonizes well with the doctrine that the Christian's union with the Son in his humanity brings him into union with one who contains in himself, in the Apostle Paul's words, "all the fullness of deity" and not a part. (See also: Divinization (Christian)). Perichoresis provides an intuitive figure of what this might mean. The Son, the eternal Word, is from all eternity the dwelling place of God; he is the "Father's house", just as the Son dwells in the Father and the Spirit; so that, when the Spirit is "given", then it happens as Jesus said, "I will not leave you as orphans; for I will come to you."^{[ John 14:18]}

According to the words of Jesus, married persons are in some sense no longer two but are joined into one.^{[ Mark 10:7–8]} Therefore, Orthodox theologians also see the marriage relationship as an image, or " icon" of the Trinity, relationships of communion in which, in the words of St. Paul, participants are "members one of another". As with marriage, the unity of the church with Christ is similarly considered in some sense analogous to the unity of the Trinity, following the prayer of Jesus to the Father, for the church, that "they may be one, even as we are one".^{[ John 17:22]}

Eternal generation and procession

Trinitarianism affirms that the Son is "begotten" (or "generated") of the Father and that the Spirit "proceeds" from the Father, but the Father is "neither begotten nor proceeds". The argument over whether the Spirit proceeds from the Father alone, or from the Father and the Son, was one of the catalysts of the Great Schism, in this case concerning the Western addition of the Filioque clause to the Nicene Creed. The Roman Catholic Church teaches that, in the sense of the Latin verb procedere (which does not have to indicate ultimate origin and is therefore compatible with proceeding through), but not in that of the Greek verb ἐκπορεύεσθαι (which implies ultimate origin), the Spirit "proceeds" from the Father and the Son, and the Eastern Orthodox Church, which teaches that the Spirit "proceeds" from the Father alone, has made no statement on the claim of a difference in meaning between the two words, one Greek and one Latin, both of which are translated as "proceeds". The Eastern Orthodox Churches object to the Filioque clause on ecclesiological and theological grounds, holding that "from the Father" means "from the Father alone".

This language is often considered difficult because, if used regarding humans or other created things, it would imply time and change; when used here, no beginning, change in being, or process within time is intended and is excluded. The Son is generated ("born" or "begotten"), and the Spirit proceeds, eternally. Augustine of Hippo explains, "Thy years are one day, and Thy day is not daily, but today; because Thy today yields not to tomorrow, for neither does it follow yesterday. Thy today is eternity; therefore Thou begat the Co-eternal, to whom Thou saidst, 'This day have I begotten Thee.'"^{[ Ps 2:7]}

Most Protestant groups that use the creed also include the Filioque clause. However, the issue is usually not controversial among them because their conception is often less exact than is discussed above (exceptions being the Presbyterian Westminster Confession 2:3, the London Baptist Confession 2:3, and the Lutheran Augsburg Confession 1:1–6, which specifically address those issues).

Economic and ontological Trinity

The economic Trinity refers to the acts of the triune God with respect to the creation, history, salvation, the formation of the Church, the daily lives of believers, etc. and describes how the Trinity operates within history in terms of the roles or functions performed by each Person of the Trinity—God's relationship with creation. The ontological (or essential or immanent) Trinity speaks of the interior life of the Trinity^{[ John 1:1–2]}—the reciprocal relationships of Father, Son, and Spirit to each other without reference to God's relationship with creation.

The ancient Nicene theologians argued that everything the Trinity does is done by Father, Son, and Spirit working in unity with one will. The three persons of the Trinity always work inseparably, for their work is always the work of the one God. Because of this unity of will, the Trinity cannot involve the eternal subordination of the Son to the Father. Eternal subordination can only exist if the Son's will is at least conceivably different from the Father's. But Nicene orthodoxy says it is not. The Son's will cannot be different from the Father's because it is the Father's. They have but one will as they have but one being. Otherwise they would not be one God. If there were relations of command and obedience between the Father and the Son, there would be no Trinity at all but rather three gods. On this point St. Basil observes "When then He says, 'I have not spoken of myself', and again, 'As the Father said unto me, so I speak', and 'The word which ye hear is not mine, but [the Father's] which sent me', and in another place, 'As the Father gave me commandment, even so I do', it is not because He lacks deliberate purpose or power of initiation, nor yet because He has to wait for the preconcerted key-note, that he employs language of this kind. His object is to make it plain that His own will is connected in indissoluble union with the Father. Do not then let us understand by what is called a 'commandment' a peremptory mandate delivered by organs of speech, and giving orders to the Son, as to a subordinate, concerning what He ought to do. Let us rather, in a sense befitting the Godhead, perceive a transmission of will, like the reflexion of an object in a mirror, passing without note of time from Father to Son."

In explaining why the Bible speaks of the Son as being subordinate to the Father, the great theologian Athanasius argued that scripture gives a "double account" of the son of God—one of his temporal and voluntary subordination in the incarnation, and the other of his eternal divine status. For Athanasius, the Son is eternally one in being with the Father, temporally and voluntarily subordinate in his incarnate ministry. Such human traits, he argued, were not to be read back into the eternal Trinity.

Like Athanasius, the Cappadocian Fathers also insisted there was no economic inequality present within the Trinity. As Basil wrote: "We perceive the operation of the Father, Son, and Holy Spirit to be one and the same, in no respect showing differences or variation; from this identity of operation we necessarily infer the unity of nature."

Augustine also rejected an economic hierarchy within the Trinity. He claimed that the three persons of the Trinity "share the inseparable equality one substance present in divine unity". Because the three persons are one in their inner life, this means that for Augustine their works in the world are one. For this reason, it is an impossibility for Augustine to speak of the Father commanding and the Son obeying as if there could be a conflict of wills within the eternal Trinity.

John Calvin also spoke at length about the doctrine of the Trinity. Like Athanasius and Augustine before him, he concluded that Philippians 2:4–11 prescribed how scripture was to be read correctly. For him the Son's obedience is limited to the incarnation and is indicative of his true humanity assumed for human salvation.

Much of this work is summed up in the Athanasian Creed. This creed stresses the unity of the Trinity and the equality of the persons. It ascribes equal divinity, majesty, and authority to all three persons. All three are said to be "almighty" and "Lord" (no subordination in authority; "none is before or after another" (no hierarchical ordering); and "none is greater, or less than another" (no subordination in being or nature)). Thus, since the divine persons of the Trinity act with one will, there is no possibility of hierarchy-inequality in the Trinity.

Catholic theologian Karl Rahner went so far as to say:

The "economic" Trinity is the "immanent" Trinity and the "immanent" Trinity is the "economic" Trinity.

Logical coherence

In Christian tradition the Trinity is a mystery of faith revealed in scripture, beyond human understanding. Theological explanations thus tend to lack or avoid a logical or philosophical foundation. In his explanation of the doctrine of the Trinity, Augustine pointed out that Jesus spoke in similitudes and would later reveal the Father more plainly. Despite his lengthy exposition to explain the Trinity in light of scripture, Augustine states that an explanation is beyond human language, and that the definition of the Trinity as three persons is but a similitude needed in order to express it. Augustine concludes that one must believe before one understands, and that the Trinity must remain unknown. After this conclusion Augustine then attempted to describe analogies of the Trinity in love itself and in the mind of man.

Hilary of Poitiers stressed that as God is infinite, eternal and omnipresent, his true nature is unfathomable, and that "words cannot describe Him". He notes that scripture states no one knows the Father except the Son. As to how the Son could be begotten, and yet not be created, he admits that it is a mystery, and confesses his ignorance at understanding it, for the Son had not yet made revelation concerning this matter. When Jesus said that He and His Father are one, he interprets it as one nature, but two persons. Again it is a mystery: "There cannot be one Person only, for He speaks not of Himself; and, conversely, They cannot be separate and divided when the One speaks through the voice of the Other. These words are the revelation of the mystery of Their unity." Because they share one nature the doctrine is "guiltless of ditheism".

Beginning around the 12th century, theology began to be influenced by Scholasticism, which is a method based on dialectical reasoning. This can be seen in the works of Thomas Aquinas, who thought that both faith and reason are necessary in Christian theology. The names of Father, Son and Holy Spirit signify the procession or emanation of the Divine. This act of procession is comparable to how an idea is conceived in the intellect; and this came forth from God as the Word. This can only be understood via similitudes, and not literally understood through material bodies. Moreover, there are two processions in God, one of the intellect (the Word) and one of the will or love. In regards to the Trinity of persons, Aquinas lists the following objection:

It would seem that there are not several persons in God. For person is the individual substance of a rational nature. If then there are several persons in God, there must be several substances; which appears to be heretical.

In answer to this objection, he redefines the word "person" as "a relation subsisting in the Divine nature". Thus properties found in God, such as goodness and wisdom, are distinguishable, but subsist together as one. But then Aquinas comes to the question, Why three? And, three what? To the first question, he answers because scripture says so, and to the second question, he answers "three persons".

In contrast to Joachim of Fiore's historicization of the Trinity, there have been recent philosophical attempts to defend the logical coherency of Trinity by men such as Peter Geach. Regarding the formulation suggested by Geach, not all philosophers would agree with its logical coherency. Geach suggested that "a coherent statement of the doctrine is possible on the assumption that identity is always relative to a sortal term".

The Canadian philosopher-theologian, Bernard Lonergan, attempted to argue for the logical coherency of the Trinity by analogy with the operations of the human subject (the psychological analogy). It is chiefly in his work "The Triune God: Systematics" that he draws on his abstract phenomenology to attempt to show this logical inner coherency in the Trinity doctrine. He saw himself as doing nothing more than standing in the tradition of Augustine and Aquinas on this issue and not based on the Bible.

Biblical background

From the Old Testament the early church retained the conviction that God is one. The New Testament does not use the word Τριάς (Trinity) nor explicitly teach the Nicene trinitarian doctrine, but there are several passages which use twofold and threefold patterns to speak of God. Binitarian passages include Rom. 8:11, 2 Cor. 4:14, Galatians 1:1, Eph. 1:20, 1 Tim. 1:2, 1 Pet. 1:21, and 2 John 1:13. Passages which refer to the Godhead with a threefold pattern include Matt. 28:19, 1 Cor. 6:11 and 12:4ff., Gal. 3:11–14, Heb. 10:29, and 1 Pet. 1:2. These passages provided the material with which Christians would develop doctrines of the Trinity. Reflection by early Christians on passages such as the Great Commission: "Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit"^{[ Matt 28:19]} and Paul the Apostle's blessing: "The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all",^{[ 2 Cor. 13:14]} while at the same time the Jewish Shema Yisrael: "Hear, O Israel: the Lord our God, the Lord is one"^{[ Deuteronomy 6:4]} led the early Christians to question how the Father, Son, and Holy Spirit are "one". Later, the diverse references to God, Jesus, and the Spirit found in the New Testament were systematized into a Trinity—one God subsisting in three persons and one substance—to combat heretical tendencies of how the three are related and to defend the church against charges of worshiping two or three gods.

Some scholars dispute the idea that support for the Trinity can be found in the Bible, and argue that the doctrine is the result of theological interpretations rather than sound exegesis of scripture. The concept was expressed in early writings from the beginning of the 2nd century forward, and other scholars hold that the way the New Testament repeatedly speaks of the Father, the Son, and the Holy Spirit is such as to require one to accept a trinitarian understanding.

The Comma Johanneum, 1 John 5:7, is a disputed text which states: "For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one." However, this passage is not considered to be part of the genuine text, and most scholars agree that the phrase was a gloss.

Jesus as God

The Gospel of John has been seen as especially aimed at emphasizing Jesus' divinity, presenting Jesus as the Logos, pre-existent and divine, from its first words, "In the beginning was the Word, and the Word was with God, and the Word was God."^{[ John 1:1]} The Gospel of John ends with Thomas's apparent confession of faith to Jesus, "My Lord and my God!"^{[ John 20:28]} There is no significant tendency among modern scholars to deny that John 1:1 and John 20:28 identify Jesus with God. John also portrays Jesus as the agent of creation of the universe.

There are also a few possible biblical supports for the divinity of Jesus found in the Synoptic Gospels. The Gospel of Matthew, for example, quotes Jesus as saying, "All things have been handed over to me by my Father."^{[ Mt 11:27]} This is similar to John, who wrote that Jesus said, "All that the Father has is mine."^{[ John 16:15]} These verses have been quoted to defend the omnipotence of Christ, having all power, as well as the omniscience of Christ, having all wisdom.

Expressions also in the Pauline epistles have been interpreted as attributing divinity to Jesus. They include: "For by him all things were created: things in heaven and on earth, visible and invisible, whether thrones or powers or rulers or authorities; all things were created by him and for him"^{[ Colossians 1:16]} and "For in Christ all the fullness of the Deity lives in bodily form",^{[ Colossians 2:9]} and in Paul the Apostle's claim to have been "sent not from men nor by man, but by Jesus Christ and God the Father".^{[ Galatians 1:1]}

Some have suggested that John presents a hierarchy when he quotes Jesus as saying, "The Father is greater than I",^{[ 14:28]} a statement which was appealed to by nontrinitarian groups such as Arianism. However, Church Fathers such as Augustine of Hippo argued this statement was to be understood as Jesus speaking in the form of a man.

Holy Spirit as God

As the Arian controversy was dwindling down, the debate moved from the deity of Jesus Christ to the equality of the Holy Spirit with the Father and Son. On one hand, the Pneumatomachi sect declared that the Holy Spirit was an inferior person to the Father and Son. On the other hand, the Cappadocian Fathers argued that the Holy Spirit was an equal person to the Father and Son.

Although the main text used in defense of the deity of the Holy Spirit was Matthew 28:19, Cappadocian Fathers such as Basil the Great argued from other verses such as "But Peter said, 'Ananias, why has Satan filled your heart to lie to the Holy Spirit and to keep back for yourself part of the proceeds of the land? While it remained unsold, did it not remain your own? And after it was sold, was it not at your disposal? Why is it that you have contrived this deed in your heart? You have not lied to men but to God.'"^{[ Acts 5:3–4]}

Another passage the Cappadocian Fathers quoted from was "By the word of the Lord the heavens were made, and by the breath of his mouth all their host."^{[ Psalm 33:6]} According to their understanding, because "breath" and "spirit" in Hebrew are both "רוּחַ" ("ruach"), Psalm 33:6 is revealing the roles of the Son and Holy Spirit as co-creators. And since, according to them, because the holy God can only create holy beings such as the angels, the Son and Holy Spirit must be God.

Yet another argument from the Cappadocian Fathers to prove that the Holy Spirit is of the same nature as the Father and Son comes from "For who knows a person's thoughts except the spirit of that person, which is in him? So also no one comprehends the thoughts of God except the Spirit of God."^{[ 1Cor. 2:11]} They reasoned that this passage proves that the Holy Spirit has the same relationship to God as the spirit within us has to us.

The Cappadocian Fathers also quoted, "Do you not know that you are God's temple and that God's Spirit dwells in you?"^{[ 1Cor. 3:16]} and reasoned that it would be blasphemous for an inferior being to take up residence in a temple of God, thus proving that the Holy Spirit is equal with the Father and the Son.

They also combined "the servant does not know what his master is doing"^{[ John 15:15]} with 1 Corinthians 2:11 in an attempt to show that the Holy Spirit is not the slave of God, and therefore his equal.

The Pneumatomachi contradicted the Cappadocian Fathers by quoting, "Are they not all ministering spirits sent out to serve for the sake of those who are to inherit salvation?"^{[ Hebrews 1:14]} in effect arguing that the Holy Spirit is no different than other created angelic spirits. The Church Fathers disagreed, saying that the Holy Spirit is greater than the angels, since the Holy Spirit is the one who grants the foreknowledge for prophecy^{[ 1Cor. 12:8–10]} so that the angels could announce events to come.

The usage of the word "paraclete" (Greek: parakletos) for the Holy Spirit in John 14:16, which can be translated as advocate, intercessor, counsellor or protector, and the Holy Spirit's essence and action characterized by truth, as all three persons of the Trinity are linked with truth (see v. 17), are seen as arguments that he is a divine person; especially that Jesus calls him another counsellor, in this way expressing that the Holy Spirit is a person equal to himself.

Old Testament foreshadowing

In addition, the Old Testament has also been interpreted as foreshadowing the Trinity, by referring to God's word,^{[ Ps 33:6]} his spirit,^{[ Isa 61:1]} and Wisdom,^{[ Prov 9:1]} as well as narratives such as the appearance of the three men to Abraham.^{[ Gen 18]} However, it is generally agreed that it would go beyond the intention and spirit of the Old Testament to correlate these notions directly with later Trinitarian doctrine.

Some Church Fathers believed that a knowledge of the mystery was granted to the prophets and saints of the Old Testament, and that they identified the divine messenger of Genesis 16:7, 21:17, 31:11, Exodus 3:2 and Wisdom of the sapiential books with the Son, and "the spirit of the Lord" with the Holy Spirit. Other Church Fathers, such as Gregory Nazianzen, argued in his Orations that the revelation was gradual, claiming that the Father was proclaimed in the Old Testament openly, but the Son only obscurely, because "it was not safe, when the Godhead of the Father was not yet acknowledged, plainly to proclaim the Son".

Genesis 18–19 has been interpreted by Christians as a Trinitarian text. The narrative has the Lord appearing to Abraham, who was visited by three men.^{[ Gen 18:1–2]} Then in Genesis 19, "the two angels" visited Lot at Sodom. The interplay between Abraham on the one hand, and the Lord/three men/the two angels on the other was an intriguing text for those who believed in a single God in three persons. Justin Martyr, and John Calvin similarly, interpreted it such that Abraham was visited by God, who was accompanied by two angels. Justin supposed that the God who visited Abraham was distinguishable from the God who remains in the heavens, but was nevertheless identified as the (monotheistic) God. Justin appropriated the God who visited Abraham to Jesus, the second person of the Trinity.

Augustine, in contrast, held that the three visitors to Abraham were the three persons of the Trinity. He saw no indication that the visitors were unequal, as would be the case in Justin's reading. Then in Genesis 19, two of the visitors were addressed by Lot in the singular: "Lot said to them, 'Not so, my lord.'"^{[ Gen 19:18 KJV]} Augustine saw that Lot could address them as one because they had a single substance, despite the plurality of persons. Some Christians see indications in the Old Testament of a plurality and unity in God, an idea that is rejected by Judaism.

According to Swedenborg, the three angels which appeared to Abraham do represent the Trinity, but a Trinity of one being: the Divine Itself, the Divine Human and the Divine Proceeding. That one being is represented is indicated by the fact that they are referred to in the singular as Jehovah and Lord. The reason why only two of the angels went to visit Sodom and Gomorrah is that they represent the Divine Human and the Divine Proceeding, and to those aspects of the Divine belongs judgment, as Jesus declared that all judgment was entrusted by the Father to the Son.^{[ John 5:22]} The three angels did indeed appear to Abraham as three men, but they are only a symbolic representation of the Trinity, which should not be taken literally as three distinct persons. In the Old Testament, Swedenborg finds the earliest direct reference to a Trine in the Divinity in the account of Moses' encounter with the Lord in Exodus which states, "And Jehovah passed by upon his face, and called, Jehovah, Jehovah, a God merciful and gracious."^{[ Exodus 34:6]}

Some Christians interpret the theophanies or appearances of the Angel of the Lord as revelations of a person distinct from God, who is nonetheless called God. This interpretation is found in Christianity as early as Justin Martyr and Melito of Sardis, and reflects ideas that were already present in Philo. The Old Testament theophanies were thus seen as Christophanies, each a "preincarnate appearance of the Messiah".

Non-orthodoxy

Non-orthodox views of the Christian trinitarian God have also been suggested by process theologians like Lewis S. Ford, who endorse the entitative view of God as timeless and eternal concrescence, but interpret the Whiteheadian natures of God (primordial nature, consequent nature, and superjective nature) in a trinitarian way. Other process theologians like Joseph A. Bracken consider the three divines persons, each understood in the Neo-Whiteheadian societal view of God sensu Charles Hartshorne and David Ray Griffin, as constituting a primordial field of divine activity.

Artistic depictions

The Trinity is most commonly seen in Christian art with the Spirit represented by a dove, as specified in the Gospel accounts of the Baptism of Christ; he is nearly always shown with wings outspread. However depictions using three human figures appear occasionally in most periods of art.

By the end of the 15th century, larger representations, other than the Throne of Mercy, became effectively standardised, showing an older figure in plain robes for the Father, Christ with his torso partly bare to display the wounds of his Passion, and the dove above or around them. In earlier representations both Father, especially, and Son often wear elaborate robes and crowns. Sometimes the Father alone wears a crown, or even a papal tiara.

Nontrinitarianism

Nontrinitarianism (or antitrinitarianism) refers to monotheistic belief systems, primarily within Christianity, which reject the doctrine of the Trinity. Nontrinitarian views differ widely on the nature of God, Jesus, and the Holy Spirit. Various nontrinitarian views, such as Adoptionism, Monarchianism and Arianism existed prior to the formal definition of the Trinity doctrine in 325, 360, and 431 AD, at the Councils of Nicaea, Constantinople, and Ephesus. Nontrinitarianism was later renewed in the Gnosticism of the Cathars in the 11th through 13th centuries, in the Age of Enlightenment of the 18th century, and in some groups arising during the Second Great Awakening of the 19th century.

Modern nontrinitarian groups or denominations include Christadelphians, Christian Scientists, The Church of Jesus Christ of Latter-day Saints (Mormons), Dawn Bible Students, Friends General Conference, Iglesia ni Cristo, Jehovah's Witnesses, La Luz del Mundo, Living Church of God, Oneness Pentecostals, Members Church of God International, Unitarian Universalist Christians and the United Church of God. Islam, which considers Jesus a prophet but not divine, teaches the absolute indivisibility of a supremely sovereign and transcendent god (see God in Islam), and is distinctly anti-trinitarian as several verses of the Koran teach that the doctrine of Trinity is blasphemous.