Introduction

The word “trinity” is at the core of Christian belief even though the word itself does not appear in the Bible.

Why is that?

The church’s use of the word “trinity” reflects its realization that it needed to use language from outside the Bible in order to explain the confessions of faith handed down from the apostles. The concept of the trinity is within the Bible, but the church didn’t have the language to articulate it at first. Language brings concepts into focus. Because of its implementation, the word “trinity” brings the concept of God into sharper focus.

The Problem of Articulating God’s Unity and Plurality of Persons

The theological problem of the late third century was how to articulate the plurality of persons within God while maintaining the unity of God. The plurality of divine persons was easy for the ancient world to grasp, but confessing that those divine persons were simultaneously distinct from one an other and unified into one God did not make sense.

If a Christian confessed the plurality of divine persons, then his contemporaries would view him as a tritheist. Likewise, if that Christian confessed absolute unity within God while also confessing a plurality of divine roles or functions, then his contemporaries concluded the unified Christian God changes how He reveals Himself within the world.¹ For example, they would assume God is one person who reveals Himself in three forms: Father, Son, and Holy Spirit.

Neither of these conclusions aligned with the apostolic witness in Scripture or tradition, so the church saw the need to learn how to articulate its confessions.

The Church Was At Risk of Losing Distinct Catholicity

Maintaining Catholicity

Precise language was necessary for maintaining the church’s understanding of God and the gospel because catholicity and distinctiveness from Platonism were essential. Thinkers in the East and West began emphasizing different truths about God. The West emphasized the unity of God, while the East emphasized the plurality of divine persons within the Godhead.² J. N. D. Kelly, Early Christian Doctrines (New York: Harper One, 1978), 109–110. These regional emphases posed a problem because they represented each region’s starting point when thinking about God. Without clarity and precision, the churches in Alexandria and Rome ran the risk of talking past one another in their attempts to articulate true doctrine. This threatened catholicity, which is itself part of the gospel message.

Remaining Distinct from Platonism

Additionally, the Mediterranean world was heavily influenced by Platonism, and this influence began seeping into the church, particularly in Alexandria. Origen was a leading figure in the Alexandrian church in the third century, and he propelled the church’s understanding of God’s plurality of persons. However, Origen still struggled to articulate the church’s confession about the Son without borrowing language from the Platonism.

Platonism asserted a divine hierarchy with subordinate beings, but this idea is fundamentally opposed to what the church believed about God. Subordination is different than submission. A subordinate Son means the Son owes His existence to the Father. If this were true, then the Father and Son could not be equally divine nor could they be united as one. The Son would be of a lower divine rank. Submission, on the other hand, allows the Son to be equal to the Father in every way of His divine being. The apostolic belief that the Son is begotten is distinct from the Son being subordinate.

We can see Origen wrestling with these ideas in the following quotes. In the first quote, Origen affirms the apostolic confession about the Son being of the same divine essence as the Father. The second quote illustrates Origen’s difficulty in expressing how these equally divine persons (the Father and the Son) relate to one another without using the language of Platonism:

“In order, however, to arrive at a fuller understanding of the manner in which the Saviour is the figure of the person or subsistence of God… to show that the Son of God, who was in the form of God, divesting Himself (of His glory), makes it His object, by this very divesting of Himself, to demonstrate to us the fulness of His deity.”

Origen, ‘First Principles’ 1.2.8, emphasis added

“Wherefore we have always held that God is the Father of His only-begotten Son, who was born indeed of Him, and derives from Him what He is.“

Origen, ‘First Principles’ 1.2.2, emphasis added

Origen helped clarify what the church meant by the Son’s divinity. But more precision was needed. A divine Son who derived His essence from the Father is less than a fully divine Son. What language could be used to capture the plurality of divine persons and the un-compartmentalized unity of God?

This is where Tertullian’s contribution helped the church.

The Heresy of Praxeas and the Articulation of God as a “Trinity”

Tertullian was a theologian in the West. One of his most influential works is called Against Praxeas.

The Heresy of Praxeas

Praxeas was the individual whom Tertullian claimed brought certain heresies to Rome. Modern scholars debate as to whether Praxeas was a nickname for other active heretics (such as Epigonus or Callistus) or if he was his own person.³ Stokes, G. T. “Praxeas.” In A Dictionary of Christian Biography, Literature, Sects and Doctrines, edited by William Smith and Henry Wace. Vol. I–IV. London: John Murray, 1877–1887.

Praxeas advocated for the heresies of ‘Monarchianism’ and ‘Patripassianism’. Monarchianism affirms the deity of Christ, but it denies the plurality of divine persons. Monarchists seek to preserve the ‘monarchy’ of God by saying God’s unity is so absolute that there is only one divine person. Any plurality of persons is considered polytheism to a Monarchist because they believe distinct persons cannot be united in absolute unity. Sabellianism, more commonly known as ‘Modalism’ is one form of Monarchianism.

Patripassianism is a logical outgrowth of Monarchianism. Since Monarchists deny the plurality of divine persons, they have to affirm one of the following: Patripassianism or Sabellianism (‘Modalism’). Patripassianism claims it was the Father who entered into the Virgin Mary’s womb, was born, and suffered on the cross.⁴ hence the nature of the compound ‘Patripassianism’: Patri (from Latin Pater) + Passianism (from Latin Passio meaning “suffering). Sabellianism is more sophisticated. It also affirms only one divine person, but it claims that divine person performs multiple functions and reveals Himself in multiple modes – hence the nickname ‘Modalism’. In this view, the ‘persons’ of the trinity within the Bible are actually modes of expression from the single divine person – God expresses Himself sometimes as the Father, sometimes as the Son, and sometimes as the Holy Spirit.

According to Tertullian, Praxeas brought the heretical ideas of Monarchianism and Patripassianism to Rome.

But why were they heretical, and how did Tertullian know they were heretical?

The Truth of Unity and Plurality of God

Tertullian asserted that Praxeas’ teachings were not alternative interpretations. They were verifiably false and in violation of the apostolic catholicity. In fact, Tertullian called Praxeas a “pretender of yesterday” because he was simply the latest in a long line of individuals who contradicted the true teaching of the gospel.⁵ Against Praxeas, II.

But on what grounds could Tertullian know this with certainty?

After articulating the core of Patripassianism, Tertullian makes two statements that reveal the source of his belief that Praxeas must be in error:

“We, however, as we indeed always have done (and more especially since we have been better instructed by the Paraclete, who leads men indeed into all truth)… this rule of faith has come down to us from the beginning of the gospel.”

Tertullian ‘Against Praxeas’ ch.II, emphasis added

These two statements bookend the content of that “rule of faith” that was passed down from the beginning. Here, Tertullian offers us an understanding of what the earliest Christians believed, and you will notice it is similar to the Apostle’s Creed and the Nicene Creed, both of which were written after Tertullian.

“Rule of Faith” from Tertullian’s Against Praxeas, ch.II	The Apostles’ Creed	The Nicene Creed
[We] believe that there is one only God, but under the following dispensation, or οἰκονομία, as it is called, that this one only God has also a Son, His Word, who proceeded from Himself, by whom all things were made, and without whom nothing was made. Him we believe to have been sent by the Father into the Virgin, and to have been born of her—being both Man and God, the Son of Man and the Son of God, and to have been called by the name of Jesus Christ; we believe Him to have suffered, died, and been buried, according to the Scriptures, and, after He had been raised again by the Father and taken back to heaven, to be sitting at the right hand of the Father, and that He will come to judge the quick and the dead; who sent also from heaven from the Father, according to His own promise, the Holy Ghost, the Paraclete, the sanctifier of the faith of those who believe in the Father, and in the Son, and in the Holy Ghost.	I believe in God the Father, Almighty, Maker of heaven and earth And in Jesus Christ, his only begotten Son, our Lord Who was conceived by the Holy Ghost, born of the Virgin Mary Suffered under Pontius Pilate; was crucified, dead and buried; He descended into hell The third day he rose again from the dead He ascended into heaven, and sits at the right hand of God the Father Almighty From thence he shall come to judge the quick and the dead I believe in the Holy Ghost I believe a holy catholic church; the communion of saints The forgiveness of sins The resurrection of the body And the life everlasting. Amen.	I believe in one God, the Father Almighty, Maker of heaven and earth, and of all things visible and invisible. And in one Lord Jesus Christ, the only-begotten Son of God, begotten of the Father before all worlds; God of God, Light of Light, very God of very God; begotten, not made, being of one substance with the Father, by whom all things were made. Who, for us men for our salvation, came down from heaven, and was incarnate by the Holy Spirit of the virgin Mary, and was made man; and was crucified also for us under Pontius Pilate; He suffered and was buried; and the third day He rose again, according to the Scriptures; and ascended into heaven, and sits on the right hand of the Father; and He shall come again, with glory, to judge the quick and the dead; whose kingdom shall have no end. And I believe in the Holy Ghost, the Lord and Giver of Life; who proceeds from the Father and the Son; who with the Father and the Son together is worshipped and glorified; who spoke by the prophets. And I believe one holy catholic and apostolic Church. I acknowledge one baptism for the remission of sins; and I look for the resurrection of the dead, and the life of the world to come. Amen.

Thus, Tertullian’s disagreement with Praxeas wasn’t merely a matter of interpretation. It was a matter of aligning with the original gospel message. Disagreeing with the rule of faith was to disagree with the gospel message as it had been preached and passed down since the beginning. Tertullian’s articulation of the rule of faith also illustrates that the church always knew what it believed, knew those beliefs were distinct yet united in catholicity, and knew when someone’s teaching didn’t align with it. It simply had to learn how to articulate its beliefs in response to heretical challenges as they emerged.

Unity and Plurality Preserved as “Trinity”

So how did Tertullian explain the reality of God’s unity and plurality of divine persons?

By coming up with the description of God as “a trinity.” God is one, thus the monarchy of God is preserved. At the same time, God is three distinct persons. Thus the “instruction and protection of divine persons” is preserved.⁶ Against Praxeas, II.

We learn from Tertullian that the heresy of Praxeas “supposes itself to posses the pure truth, in thinking that one cannot believe in One Only God in any other way than by saying that the Father, the Son, and the Holy Ghost are the very selfsame Person.”

In contrast, Tertullian confesses the truth of God’s monarchy and plurality of persons in the following way:

“As if in this way also one were not All, in that All are of One, by unity (that is) of substance; while the mystery of the dispensation is still guarded, which distributes the Unity into a Trinity, placing in their order the three Persons—the Father, the Son, and the Holy Ghost: three, however, not in condition, but in degree; not in substance, but in form; not in power, but in aspect; yet of one substance, and of one condition, and of one power, inasmuch as He is one God, from whom these degrees and forms and aspects are reckoned, under the name of the Father, and of the Son, and of the Holy Ghost.”

Tertullian, ‘Against Praxeas’ ch.II, emphasis added

Conclusion

Thus, the mystery of God was brought into sharper focus with Tertullian’s description of God as a trinity. The word “trinity” is not in the Bible, but trinitarian belief goes back to the Apostles and was preserved generation after generation through the rule of faith. It was this tradition of teaching and understanding of the apostolic faith that allowed Tertullian and other apologists identify and refute heresies. In doing so, they also learned how to develop the best language to articulate the truthful mysteries of the faith with precision. God is three distinct persons, and those persons are united in true unity that still makes Him one.

Tertullian’s work also preserved catholicity within the church. The description of God as “a trinity” allowed theologians from the East and West to talk to one another instead of past one another. Those in the West could begin to see the theological starting point of those in the East and vice versa.

Finally, this catholicity remained distinct from Platonism and other philosophies and religions throughout the Mediterranean world. Christians could explain how their God is three distinct persons without using Platonist language of subordinationism. The threat of internal disunity as well as competing heresy spurred the church to develop the necessary language to articulate what it had always believed since the apostles.

And we still use this language today.