Defending biblical truth is often a game of whack-a-mole. One of Satan’s oldest and commonest methods of deception is to set beside the truth so many attractive counterfeits that it can hardly be distinguished in the lineup. The same serpent who lied in the garden (Genesis 3:1, 4-5) sowed heresies in the first century: the Judaizers (Acts 15:1), Docetists (1 John 4:3), and antinomians (Revelation 2:20).

When the apostles passed from the scene, false teachings did not. And the early church needed an ongoing response to the constant assault of heresies. One man who provided this response was Tertullian, an educated Roman in Carthage who was converted to Christianity as an adult and became one of its foremost defenders. His many extant writings date from the years 197-218.

“The character of the times in which we live is such as to call forth from us even this admonition,” Tertullian wrote around the year 200 in “Prescription against Heretics”: “that we ought not to be astonished at the heresies (which abound), neither ought their existence to surprise us, for it was foretold that they should come to pass.”

Nor should Christians even be surprised that false teachings “subvert the faith of some,” he added, “for their final cause is, by affording a trial to faith, to give it also the opportunity of being approved” as genuine.

Tertullian is noteworthy as the first Christian theologian to write in Latin, and for the sharp, punchy style he often employed in defense of the church.

Unfortunately, the details of Tertullian’s life are less well-known than those of other early Christians. Church historians now surmise that early biographers like Jerome and Eusebius made wrong assumptions about his life, so that “the most scholars can now say with confidence concerning Tertullian’s early life is that he was born to a non-Christian family ca. 160-170 CE, was highly educated and thus a member of the Carthaginian elite, and was married.”

Due to its relative isolation by water and desert, North Africa became a neglected part of the Roman Empire, which allowed Christians there to develop their own distinctive traditions. This allowed Tertullian the relative leisure to devote his efforts to combating heresies that spread throughout the empire, especially to Rome. Thus, Tertullian is mostly known through his writings.

Against Modalism

In an early work named after a false teacher, “Against Praxeas,” Tertullian refuted Modalism, a heresy which suggests the Father, Son, and Spirit are merely three different modes of expression of one God, not distinct persons. Praxeas “says that the Father Himself came down into the Virgin, was Himself born of her, Himself suffered, indeed was Himself Jesus Christ,” Tertullian summarized.

“Here the old serpent has fallen out with himself,” Tertullian responded, “since, when he tempted Christ after John’s baptism, he approached Him as the Son of God; surely intimating that God had a Son … ‘If you are the Son of God, command that these stones be made bread’ [Matthew 4:3].” Thus immediately he appealed to the authority of New Testament writings to prove the heresy false.

If he had microphone, Tertullian surely could have dropped it there. But he was not content to proof-text his way to victory. Tertullian continued in “Against Praxeas” to lay out a full doctrine of what Christians today call the Trinity. And we call the Godhead by that name because Tertullian gave us the language to do so.

“The mystery of the dispensation is still guarded,” he wrote, “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.”

Not only did Tertullian apparently coin the word “trinity” here, but he also borrowed Roman legal terms to define the trinity as “three persons … of one substance” (or, one could say, “essence”). More than a century later, Tertullian’s distinction between person and substance in the Godhead informed the Council of Nicaea, which imported this distinction into Greek as a part of its famous creed.

Some critics of Christianity eagerly point out that theological terms like “trinity” are found nowhere in Scripture. But that simple fact does not mean they cannot be shown from Scripture. Christian belief is submitted to the teaching of one book, and Tertullian’s theology was no exception. He grounded his notion of the Trinity with Scriptural references to Genesis 1:26 and 3:22, where God speaks in plural, and to John 1:1, where “you have two Beings — One that commands that the thing be made, and the Other that executes the order and creates.”

Thus, Tertullian showed respect for and familiarity with the Old Testament as well as the New. This became especially relevant in connection to another heresy, Gnosticism. Gnostic theology posited a fundamental distinction between an evil material world and a good spiritual world, even going so far as to claim that the Old Testament God who created the world was a different god from the one who revealed himself through Jesus Christ.

Against Gnosticism

In “Against Marcion,” Tertullian wrote that the heretic by that name “now applied to the Creator the figure of the corrupt tree bringing forth evil fruit, that is, moral evil, and then presumed that there ought to be another god, after the analogy of the good tree producing its good fruit [Matthew 7:17]. … He readily argued that in his Christ had been revealed a new and strange divinity.”

“How arrogantly do the Marcionites build up their stupid system, bringing forward a new god, as if we were ashamed of the old one! … What new god is there, except a false one?” Tertullian retorted. The very definition of God, he said, precluded the possibility of a second creator. “God is the great Supreme existing in eternity, unbegotten, unmade without beginning, without end. … That Being, then, which is the great Supreme, must needs be unique, by having no equal, and so not ceasing to be the great Supreme.”

Although changed in emphasis, Gnosticism remains one of the most prevalent heresies Christians face today. It undergirds every denial of the Creator’s good work, every attempt to divorce the Old Testament from the New, and every notion that divides a person’s body and soul, such as the claim, “I am a woman trapped in a man’s body.”

Just as in our culture, Gnostic ideas seemed highly plausible in the world of ancient Greek philosophy. But Tertullian defended Christian truth and the goodness of the natural world without shame. “Imitate, if you can, the cells of the bee, the hills of the ant, the webs of the spider, and the threads of the silkworm,” he challenged. “Nature itself, therefore, if not an Isaiah, or rather God speaking by Isaiah, will deprecatingly ask, ‘To whom will you liken me?’ [Isaiah 46:5].”

Other Writings

Tertullian wrote multiple works against Gnosticism and many other heresies. In a treatise dedicated to his wife, Tertullian defended monogamous marriage as God established it against two errors, both of which apparently came from Gnosticism. Some teachers proclaimed an ascetic lifestyle that renounced any form of sexual intimacy. Others promoted a promiscuous or polygamous lifestyle that discounted the significance of physical acts.

Tertullian wrote another treatise “On Baptism” (perhaps the first) to counter the Gnostic notion that baptism in water was unnecessary for believers. In it, he interprets baptism typologically, from the Spirit hovering over the waters (Genesis 1:2) to the crossing of the Red Sea (Exodus 14), to Jesus’s symbolic references to water in the gospel of John (John 2:1-11; 7:37-38).

Water baptism was not always required of those who believed in God, Tertullian argued, “but now that faith has been enlarged, and has become a faith which believes in His nativity, passion, and resurrection, there has been an amplification added to the sacrament, viz., the sealing act of baptism. … For the law of baptizing has been imposed, and the formula prescribed: ‘Go,’ He says, ‘teach the nations, baptizing them into the name of the Father, and of the Son, and of the Holy Spirit’ [Matthew 28:20].”

Notably, Tertullian speaks against the baptism of children in the treatise. “The delay of baptism is preferable; principally, however, in the case of little children. … Let them know how to ask for salvation,” he proposed. “If any understand the weighty import of baptism, they will fear its reception more than its delay: sound faith is secure of salvation.”

(Of course, Christian practice should be guided by the teachings of Scripture, rather than the thought of any early church figure. But Tertullian’s treatise suggests that believers’ baptism predates infant baptism.)

Montanism

However, if Tertullian were alive today, he would probably not be a Baptist but a Pentecostal. Later in his life, Tertullian seemed to join a movement known as “the New Prophecy,” or Montanism. Montanus was a Christian man in the Roman province of Phyrgia (central Turkey) who claimed to receive prophecies directly from the Holy Spirit, as did two female companions, Priscilla and Maximilla.

These prophecies largely concerned morally rigorous renewal in the church, and the movement spread quickly — all the way to North Africa. However, it was not received well by the church as a whole, and a council of bishops in the eastern empire eventually anathematized it. However, Montanist congregations continued to exist, in schism with the rest of early Christianity, for centuries. Some Montanists who followed Tertullian were eventually reconciled to the North African church by Augustine, more than 100 years later.

Assessing the Montanist movement is perplexing. On the one hand, it claimed new revelation, whereas other Christians insist that the Scriptural canon had been completed in the apostolic era. On the other hand, the movement seemed to teach no other doctrinal errors and simply exhorted Christians to lead holier lives. Still, the schism it created was a regrettable failure of Christians to live up to the unity commanded in the New Testament, as some Christians insisted they were holier than others.

Whatever the assessment one makes of Tertullian’s Montanist years, his early writings show a bold Christian apologist who thought through his faith, but who never allowed reason to triumph over the word of God. In that, Tertullian remains a model for us. He combatted heresies and left a rich legacy — especially in his thinking about the Trinity — that blessed the church for years to come.

Today, heresies still appear everywhere. They often present themselves as plausible, or at least popular, or at least a way not to offend the non-Christian culture. But Tertullian lived out the words of Psalm 119:98-99, “Your commandment makes me wiser than my enemies, for it is ever with me. I have more understanding than all my teachers, for your testimonies are my meditation.”

It is fitting here to give the last word to some of Tertullian’s most famous words. He denounced pagan Greek philosophy and the cults it spawned as “that human wisdom which pretends to know the truth, while it only corrupts it, and is itself divided into its own manifold heresies, by the variety of its mutually repugnant sects.”

“What indeed has Athens to do with Jerusalem? What concord is there between the Academy and the Church? What between heretics and Christians?” Tertullian queried. “Away with all attempts to produce a mottled Christianity of Stoic, Platonic, and dialectic composition! We want no curious disputation after possessing Christ Jesus, no inquisition after enjoying the gospel! With our faith, we desire no further belief.”