To those of us who have studied the historical development of the trinity, the Athanasian Creed is not new to us, we have “gotten the handle on Trinitarianism” as you call it.
The creed stands at the end of a long process of development. Not something handed down historically from the apostles, mind you, but developed by step by step by such principle men as Justin, Tertullian, and Origen.
The Athanasian Creed, were it around in these men’s days, would have condemned them, none of them believed Father, son, Holy Spirit as defined in this creed.
Justin Martyr, a former pagan Greek philosopher and apologist, used the Logos of Plato as a means to defend Christianity, on one hand, a means to convert the masses heavily influenced by Greek philosophic thought, on the other.
Tertullian, who came later, building upon Justin, is famously known as the first to use “persons” and “Trinity” writing against Praxeus’ oneness belief.
Origen, who came later, following Justin and Tertullian before him, added the concept of the “eternal Son.” The councils came later, the Cappadocian Fathers you mentioned, and Augustine, giving us the final product.
I don’t buy any of it. The apostles were of the Jewish monotheist tradition, the pagan philosophy would have been abhorrent to them. John’s Logos was not Plato’s or Justin’s. They were neither Trinitarian nor Arian. I believe they were, what people call today, “Oneness Pentecostals.”
Correction, I meant to say Justin was a former philosopher, after conversion becoming a Christian apologist. I should read what I type before posting it.
And exactly what was the “Jewish monotheist tradition”? Josephus who was very much part of the same world as the Apostles knew both Plato and Moses, insisted that Plato had read Moses. Many Jews, perhaps most Jews were Greek speakers. For many years Palestine was ruled by the Ptolomies, who were very friendly to Jerusalem, and Jews made up a quarter of Alexandria. Jesus himself very likely spoke some Greek although his “mission” was to Aramaic speaking Jews, by the testimony of the Gospels. Paul, though a Pharisee, came from the diaspora of the West, as did Apollos, an eloquent evangelist of whom Paul speaks favorably. Maybe what you call the Jewish monotheist tradition is the tradition of the rabbis who had to regroup, so to speak, after the destruction of the Temple, and create a non messianic/ non territorial Judaism for a now homeless Jewish nation.