Tertullian (A.D.145-220) wrote a dissertation against the modalist Praxeas who believed that God was a divine Individual who manifested Himself sometimes as the Father, sometimes as the Son, and sometimes as the Holy Spirit; yet He is just one Individual and not three. Tertullian proposed that, though there is just one God, there are three divine Individuals who comprise that one God. As far as I know, Tertullian was the first person to employ the word “Trinity.” What follows are Chapters 2, 3, and 4, of Tertullian’s writing against Praxeas. It is quoted from the Ante-Nicene Fathers series (the early Christian writers who wrote prior to the Council of Nicaea in A.D. 325), chapters 2-4:
Tertullian may have been the first to coin the word Trinity (although I know of no evidence of him being subsequently recognized as such by his immediate successors and contemporaries), but the coining of terminology doesn’t make him the first person to believe that the one and only God Most High is three distinct Persons.
We don’t have any record, as far as I know, of anyone else using the Greek word for ‘son-placement’ in Paul’s epistles either, but that doesn’t mean he was the first person to come up with the idea of children only being granted the rights and responsibilities of the family when the head of the family judges them to be sufficiently mature. Aside from lots of testimony elsewhere to this practice, including in texts preliminary to Paul’s epistles, his deployment of the concept contextually presumes that his audience already knows the typical facts of what he’s talking about.
Tertullian might be the first person to attempt to systematically present the doctrines. But his presentation presumes that these doctrines (with scriptural allusions, and in a creedal form close to the eventual Apostle’s Creed) are already known and accepted by “us”. Even if you wanted to treat the “have always” “passed down to us from the beginning” as polemic exaggeration, it still presumes established precedent of some kind prior to Tertullian; and his charge against Praxeas, aside from incoherency, is that his notion of the F/S/HS being only modal expressions (as we would say today) is a late novelty.
To be fair the other way, as an example of possible rhetorical overstatement (in terms of how long something has been going on), Tertullian also says that simple people who always constitute the majority of believers are constantly throwing out against us that we are preachers of two and three gods. This, by the same principle of testimony, at least shows evidence that objections to the total doctrinal set and how it is put together, have been going on for as long as teachers have tried to teach the total doctrinal set. How far back does that go? Five years before Tertullian writes this? Five decades? Since the apostles?
In any case, just as Tertullian states that the objections to the doctrinal set significantly precede Tertullian (although he treats Praxeas’ modalism per se as a new-fangled absolute novelty), so does Tertullian state that the doctrinal set significantly precedes Tertuillian.
There are a couple of Wiki articles - on the subject:
en.wikipedia.org/wiki/Trinity (see history section)
Yes, Trinitarianism may have been taught prior to Tertullian. But “since the apostles”? I cannot say. What I can say is that Justin Martyr (A.D. 110-165) did not subscribe to it.
Justin had a discussion with a Jewish man, Trypho (and some of his companions) which lasted several days. Justin was showing from the Hebrew writings that God had begotten His Son before all ages, and compared this begetting to lighting a small fire from a large one. Justin affirmed also that the Son shared the Name “Yahweh” with the Father. He argued that in Genesis 19:24, there were two individuals who were called “Yahweh”, One in heaven (the Father), and One on earth (the Son) who was talking to Abraham. Justin also showed from many Scriptures that the Son of God was born on earth as a human being and that He was the promised Messiah.
Both Justin and Trypho throughout their dialogue had been referring to the Holy Spirit. Clearly Trypho, a Jew, didn’t think of the spirit of God being a person apart from God. Justin apparently didn’t either. In his Dialogue, he often referred to “the spirit speaking form the person of the Father” and “the spirit speaking from the person of the Son.”
It is interesting that at one point, Justin asked Trypho this question:
If Justin had been a Trinitarian, this would have been a perfect opportunity to present the Holy Spirit as the Third Person of the Trinity. But he didn’t. Instead, he said:
The earliest Christian use of the term “Trinity” (Greek: “trias”) comes from Theophilus, bishop of Antioch (180 AD), who teaches a Trinity consisting of “God, God’s Word (Christ) and God’s Wisdom.” OT Wisdom literature personifies Lady Wisdom and has her speak as if She is a Person distinct from Yahweh (e. g. Proverbs 8). The OT never personifies the Holy Spirit in this way. Jesus speaks as if He is inspired by Wisdom personified: “Therefore, the Wisdom of God said…(Luke 11:49).”
I point this out not to lobby against the Risen Lord’s reference to Father, Son, and Holy Spirit in His baptismal formula in Matthew 28:19, but to draw attention to the fact that the creedal concept of 3 Persons in 1 and I in 3 is not explicitly biblical. Why does this matter? Not because our Trinity doctrine is false, but because it is so abstract that it draws attention away from how experiential the role of the Spirit is in conversion, sanctification, and the gifts of the Spirit. Most Christians wrongly treat the regenerating work of the Spirit as if the Spirit is automatically received upon profession of faith with no need for a corroborating experience of the Spirit’s arrival and indwelling presence.