A study of the doctrine of the Trinity as its understanding developed in the early centuries of the church.


This essay will survey the developing understanding of the Christian doctrine of the Trinity in the first centuries of the Christian church and conclude with some reflections for today’s Christian.


German theologian and church historian Adolf von Harnack (1851–1930) famously declared that Christian doctrinal development “is a work of the Greek spirit on the soil of the gospel” (History of Dogma, I, 17). According to Harnack, trinitarian doctrine in the early church was an imposition on the biblical understanding of God. On the contrary, the early church was trinitarian because the Bible is trinitarian. The apostolic testimony to Jesus’ person and work, the Old Testament declaration of God’s sovereign work and prophetic expectation, as well as the experience of and testimony to the work of the Spirit in the life of the church (and in the pages of Old Testament scripture) all revealed the threeness of God. Reflecting on Scripture and the person and work of Christ, the early church developed an increasing trinitarian consciousness. This consciousness expressed itself in worship, theological reflection, and pastoral encouragement. While the word Trinity itself was a development, the belief in God as triune has been the bedrock of Christian faith from the beginning.


Around 110 AD, a pastor from Antioch name Ignatius (c. 35–c. 110) wrote several letters to various churches on his way to his eventual martyrdom. His trinitarian consciousness was informed by a discernible mix of Old Testament and New Testament writings, though exact quotations were minimal. His affirmation of the Son’s relation to the Father even had a certain hymnic quality. The clearest trinitarian imagery and most profound statements can be found in his letter to the Ephesians. Comparing church unity to a chorus, Ignatius instructs them to “[take] your pitch from God [so that] you may sing in unison with one voice through Jesus Christ to the Father, in order that he may both hear you and, on the basis of what you do well, acknowledge that you are members of his Son” (Letter to the Ephesians 4.2). Noting the trinitarian foundation of the church, Ignatius describes believers like “stones of a temple, prepared beforehand for the building of God the Father, hoisted up to the heights by the crane of Jesus Christ, which is the cross, using as a rope the Holy Spirit” (Letter to the Ephesians 9.1). A few years after Ignatius, Polycarp the bishop of Smyrna (69–156) also demonstrated his trinitarian consciousness before his martyrdom: “I glorify you, through the eternal and heavenly High Priest, Jesus Christ, your beloved Son, through whom to you, with him and the Holy Spirit, be glory both now and for the ages to come” (Martyrdom of Polycarp, 14).

Similar to Polycarp, early apologists for the Christian faith did not shy away from a trinitarian confession. Athenagoras of Athens (c. 133–190) remarked, “Who…would not be astonished to hear men who speak of God the Father, and of God the Son, and of the Holy Spirit, and who declare both their power in union and their distinction in order, called atheists?” (A Plea for the Christians, 10). Justin Martyr (100–165) described the typical baptismal routine for his readers: “In the name of God, the Father and Lord of the universe, and of our Savior Jesus Christ, and of the Holy Spirit, [new converts] then receive the washing with water” (First Apology, 61). In defending the faith, apologists asserted that Christianity worshipped the one true God revealed as Father, Son, and Spirit. This was nothing new, as many detractors assumed, but was the revealed truth from the very beginning made crystal clear through the Word made flesh (cf. John 1:14).

Irenaeus of Lyons (c.130–c. 202) presented a thorough defense of the economic Trinity, that is, how the members of the Godhead relate to one another and the history of salvation. The cooperating of the three is expressed as “the Father planning everything well and giving his commands, the Son carrying these into execution and performing the work of creating, and the Spirit nourishing and increasing [what is made]” (Against Heresies 4.38.3). In view for Irenaeus were the various teachings of Gnosticism which posited an evil creator god, and a good spiritual god with numerous lesser spiritual beings. Irenaeus affirmed the Christian faith as monotheistic, with the one true God as creator and Lord of all. Rather than seeing multiple beings, and attributing creation to a lesser evil god, Christianity affirmed one God who is creator and sustainer of all things. This one God existed as three persons and was intimately involved in the redemption of man and the cosmos.


Trinitarian reflection continued right into the third century with figures such as Tertullian of Carthage, Hippolytus of Rome, and Origen of Alexandria among others. In the early third century, Hippolytus of Rome (c. 170–c. 235) wrote a treatise entitled Against Noetus, in response to a Christian from Smyrna named Noetus who had been promoting non-biblical views of the Trinity. Noetus and others claimed that the Father as well as the Son had suffered on the cross (a belief entitled patripassianism). Hippolytus also wrote in defense of the economic Trinity: “The economy of harmony is led back to one God; for God is one. It is the Father who commands, and the Son who obeys, and the Holy Spirit who gives understanding. The Father who is above all, and the Son who is through all, and the Holy Spirit who is in all” (Against the Heresy of the One Noetus, 8; ANF 5:226). This language of “above,” “through,” and “in” would later become a point of contention among the Pnematomachian (literally translated “spirit fighters”) group in the fourth century who denied the deity of the Spirit.

Writing against a false teacher named Praxeas, Tertullian of Carthage (155–240) stated, “He put to flight the Paraclete and crucified the Father” (Against Praxeas, 1). Like other early Christian theologians, the crux of the issue was a twisting of Scripture. He asserted, “[A]ll the scriptures display both the demonstration and the distinctness of the Trinity: and from them derived also our standing rule, that speaker and person spoken of and person spoken to cannot be regarded as one and the same. (Against Praxeas, 11). The “rule” referred to the rule of faith, which was the summary of biblical teaching represented in the apostolic declaration of faith. Adherence to this rule guaranteed proper interpretation of Scripture. Responding to the error of modalism, Tertullian’s formulation became the foundation for the church’s definition of the Trinity. He maintained, “All are of one, by unity … of substance; while the mystery of the economy is still guarded, which distributes the unity into a Trinity, placing in their order the three persons—the Father, the Son, and the Holy Spirit” (Against Praxeas, 2).

Though he maintained a trinitarian belief regarding to the economy of redemption, the work of Origen of Alexandria (c. 184–c. 253) contains hints of subordinating the Son to the Father, as seen for example in his Commentary on John 13.25: “We say that the Savior, and the Holy Spirit, transcend all creatures, not by degree but by a transcendence beyond all measure. But he, [the Son, like the Holy Spirit] is transcended by the Father as much as, or even more than, he and the Holy Spirit transcend the other creatures, even the highest.” Though there seems to be a subordinationist strain in Origen, he upholds the ontological unity of God. “As light … could never exist without splendor, so neither can the Son be understood to exist without the Father” (On First Principles 4.28). Origen also provided helpful reflection in understanding the eternal generation of the Son. He asserted that “God is the Father of his only-begotten Son, who was born indeed of him, and derives from him what he is, but without any beginning” (On First Principles 1.2.2). He goes on to affirm: “The unity of nature and substance belong to the Father and Son” (On First Principles 1.2.6). Origen’s mixed thoughts on the Trinity, while never crossing heretical borders, would have significant effects on fourth-century trinitarian reflection for both orthodox as well as heretical teachers.


In the fourth century, the battle for the Trinity intensified in the midst of christological and pneumatological errors. In the early fourth century, a presbyter from Alexandria named Arius (256–336) asserted that “there was a time when the Son was not.” Emphasizing the oneness of God, Arius declared that the Son was a created being. “At the will of God, he was created before times and before ages, and gaining life and being from the Father” (Arius, Letter to Alexander; NPNF2 4:458). Though Arius granted that the Son was unique, he nonetheless maintained that he was a created being. Arius leaned upon Proverbs 8:22-31 and Colossians 1:15 for supposed biblical support of the Son’s status as a creature. These were the same passages a century earlier that Origen chose in order highlight the unique status of Christ, yet not as a created being. Arius also pointed to various passages such as John 14:28 and Mark 13:32 to show that the Son was lesser than the Father. Thus, the Council of Nicaea convened by emperor Constantine in 325 sought to address the thorny theological issue of Arianism. The council developed a creed which affirmed the full deity of the Son while also condemning specific Arian beliefs as heretical. They affirmed that the Son was homousias (Greek – “one substance”) with the Father and is “God of God, light of light, true God of true God, begotten not made.” Nicaea would not solve the problem overnight, therefore thinkers such as Athanasius of Alexandria, Hilary of Poitiers, and the Cappadocian Fathers would go on to provide significant theological defense of the biblical Trinity in the mid-to-late fourth century.

Athanasius of Alexandria (c. 296–373) served as a deacon when the Council of Nicaea took place. When he became bishop in Alexandria, he continued to champion the Nicene faith despite Arianism being favored by Constantine’s son, Emperor Constantius II (r. 337–361). Athanasius was subsequently exiled five times for his ongoing defense of Nicene orthodoxy. His primary concern was the message of the gospel. He asked, “If the Word were a creature, how could he have power to undo God’s judgment and to forgive sin, since…this is God’s prerogative only?” (Four Discourses Against Arians, 2.67; NPNF2 4:385). Athanasius asserted, alongside the conclusions of Nicaea, that the Son is of the same essence (homoousias) yet distinct, and he emphasized that the unity of nature did not make the Father and Son the same, thus avoiding modalism. Taking up the mantle from Athanasius, Hilary of Poitiers (c. 310–c. 367) would affirm the Nicene message within Western Christianity, and the Cappadocian Fathers would do so in the East. Hilary wrote his treatise On the Trinity around 360 which upheld Nicene theology, earning him the title “Athanasius of the West.”

Basil of Caesarea (329–379) and his brother Gregory Nyssa (c. 335–c. 395) alongside their mutual friend Gregory or Nazianzus (329–390)—collectively known as the Cappadocian Fathers—wrote numerous treatises on both the unity of the godhead and the unique role of each divine person. It was a spiritual exercise arising out of a concern for maintaining the gospel. They fought for the truth that God was one in essence (Greek – ousia) while three in person (Greek – hypostasis). Basil wrote, “The term ousia is common [to all] … while hypostasis is contemplated in the special property of Fatherhood, Sonship, or the power to sanctify” (Letter 214.4). Similarly Gregory Nazianzus taught, “The Godhead is one in three, and the three are one, in whom the Godhead is, or to speak more accurately, who are the Godhead” (Oration 39.11). Gregory Nyssa followed along the same lines stating, “Each of the three persons possess unity … by reason of the identify of essence and power” (Against Eunomius, 1.36). By the close of the fourth-century, thinkers such as Athanasius, Hilary of Poitiers, and the Cappadocians had solidified the biblical teaching of Nicaea (affirmed by the subsequent Council of Constantinople in 381) as the true trinitarian doctrine of the church.


Thinkers in the fifth century provided the apex of trinitarian reflection that would solidify trinitarian theology for the next 1000 years. Augustine of Hippo (354–430) in the west and Cyril of Alexandria (c. 376–444) in the east provided a keen defense for trinitarian orthodoxy. They continued to promote belief in the unity of essence and threeness of person. In his work On the Trinity, Augustine asserted, “Whatever … is spoken of God in respect to himself, is both spoken singly of each person, that is, of the Father, and the Son, and the Holy Spirit; and together of the Trinity itself, not plurally but in the singular” (On the Trinity, 5.8.9). Augustine also articulated the view of the Spirit’s double procession from both the Father and Son because we see the Spirit proceeding from the Son as well (On the Trinity, 15.17.29). The Latin phrase filioque (“and the Son”) would become a hallmark of Western Christian trinitarian teaching, being added into the Nicene creed and later causing consternation between the Western and Eastern church.

Cyril of Alexandria was a pivotal figure within the Nestorian controversy which led to the Council of Ephesus in 431. In the incarnation, according to Cyril, “the two natures being brought together in a true union, there is of both one Christ and one Son” while also retaining their respective characteristics (Fourth Letter of Cyril to Nestorius, NPNF2 14:198). For Cyril, the eternal Son of God took upon and personally united with a human nature, both in body and soul. Subsequently, the Council of Ephesus denounced Nestorianism as heretical. Throughout his writings, including extensive commentary literature, Cyril demonstrates his indebtedness to Nicene theology from the fourth century and solidifies its place as the true biblical understanding of God as triune. The Council of Chalcedon in 451 would rely heavily upon Cyril’s teachings regarding the two natures of Christ, asserting that Christ was both human and divine “without confusion, without change, without division, without separation; the distinction of natures being in no way annulled by the union.” Chalcedon would affirm the previous theological affirmations of the Trinity and would become imbedded in the trinitarian theology of the church up to the present day.

Considerations for Evangelical Christians

Evangelicals have much to consider when it comes to trinitarian reflection in the early church. First, the early church vigorously defended the Trinity from Scripture. Understanding the Trinity was not an exercise in proof-texting or philosophical sophistry, but rather deep Holy Spirit-driven whole-Bible reading. Their trinitarian consciousness was woven throughout their writing, their worship, and their witness. Second, it is important for the church to speak correctly about the Trinity. We cannot fully grasp the depth of mystery that is the triune God, yet we should not be flippant with trinitarian doctrine either. It matters how we understand the roles of Father, Son, and Spirit in our redemption. It also matters that we take trinitarian doctrine seriously when approaching any ministry effort of the church, whether that be Sunday morning worship or a middle-school Bible study. Last, trinitarian doctrine sets Christianity apart from any other faith commitment. Muslims, Jehovah’s Witnesses, Mormons, Unitarians, and others who claim to worship God do not worship the God proclaimed by Scripture, the testimony of the apostles, and the witness of the early church. Unless the God you worship is Father, Son, and Holy Spirit then you worship a false god. The early church vigorously fought for trinitarian theology in the wake of multiple waves of heresy. We should continue to contend for it today.

Further Reading

  • Michael Haykin, Giving Glory to the Consubstantial Trinity: An Essay on the Quintessence of the Christian Faith (Free Grace Press, 2019)
  • Christopher A. Hall, Learning Theology with the Church Fathers (IVP Academic, 2002)
  • Donald Fairbairn, Life in the Trinity: An Introduction to Theology with the Help of the Church Fathers (IVP Academic, 2009)
  • William Rusch, ed. The Trinitarian Controversy (Sources of Early Christian Thought). (Fortress Press, 1980)
  • Robert Louis Wilken, The Spirit of Early Christian Thought: Seeking the Face of God (Yale University Press, 2005)

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