There are few pillars in Christian Church history that can tower one of the finest North African’s Latin theologian and apologist Tertullian (ca. 160- ca. 225 A.D.)
My interest in the life and works of Tertullian sprouted from an encounter with door-to-door Jehovah’s Witnesses. In one of our dialogues, I was handed the Watch Tower Bible And Tract Society’s brochure, “Should You Believe in the Trinity? Is Jesus Christ the Almighty God?” in which the Watch Tower Society argued that the doctrine Trinity God was alien to early Christians.
Noticing that “trinitas” appeared in the works of Tertullian, Watchtower Society contended that, “this is no proof in itself that Tertullian taught the Trinity”(Watchtower 1989: 5). It took a decade for Watchtower’s organization to discover their mistake. Contrary to what they believed, Tertullian defended not only the doctrine of Trinity God but also the deity of Christ Jesus and the bodily resurrection, among other doctrines, which they deny. The Watchtower Society admitted,
“[Tertullian] coined the formula “one substance in three persons.” Using this concept, he attempted to show that God, his Son, and the holy spirit were three distinct persons existing in one divine substance. Tertullian thus became the first to apply the Latin form of the word “trinity” to the Father, the Son, and the holy spirit.”(Watchtower 2002: 31)
In this article, I pointed out a small potion of Tertullian’s work that caused Watchtower’s organization to alter their understanding of this Northern African’s giant.
Tertullian view of Doctrine Of Trinity
Writing against Praxeas, who taught Monarchianism viz., the doctrine that held the Father, the Son and the Holy Spirit to be one and the same person, Tertullian presented one of the earliest and most robust defenses of one and only God in three distinct persons. Tertullian contended:
Bear always in mind that this is the rule of faith which I profess; by it I testify that the Father, and the Son, and the Spirit are inseparable from each other, and so will you know in what sense this is said. Now, observe, my assertion is that the Father is one, and the Son one, and the Spirit one, and that They are distinct from Each Other. [...] Father and the Son are demonstrated to be distinct; I say distinct, but not separate.(Tertullian 1885: 603)
Quoting Isaiah 42:1, 45:1 61:1(Luke 4:18) 53:1-2, Psalms 71:18, 3:1, 110:1, Tertullian argued:
Still, in these few quotations the distinction of Persons in the Trinity is clearly set forth. For there is the Spirit Himself who speaks, and the Father to whom He speaks, and the Son of whom He speaks.(ibid)
Pointing to Moses’ usage of plural phrases “us”, and “our” instead of “me” and “my” uttered by God in Genesis 1-3, Tertullian correctly reasoned, that God the Father “had already His Son close at His side, as a second Person, His own Word, and a third Person also, the Spirit in the Word, that He purposely adopted the plural phrase”(ibid).
Though Tertullian did not contend in detail the deity of the Holy Spirit, he showed that the Spirit was the third person of tres Personae, una Substantia.
Question: Did you know that the doctrine of one God in three persons was taught by early Christians?
Watchtower (1989) Should You Believe in the Trinity? Is Jesus Christ the Almighty God? Watch Tower Bible And Tract Society of Pennsylvania.
_____________ (2002) Who Is God? May 15th. Watch Tower Bible And Tract Society of Pennsylvania.
Tertullian. (1885). Tertullian In A. Roberts, J. Donaldson & A. C. Coxe (Eds.), The Ante-Nicene Fathers, Volume III: Latin Christianity: Its Founder, Tertullian (A. Roberts, J. Donaldson & A. C. Coxe, Ed.) Buffalo, NY: Christian Literature Company.
 Tertullian explained further that its “on the ground of Personality, not of Substance—in the way of distinction, not of division.”