Well, this is not very clear. I want to make it that first century Christians, there was a clear belief in "Father, Son, and Holy Spirit". What that means became clearer and clearer generation after generation.
Honnestly, this is question begging. You are assuming what must be proven. One can believe in the Father Son and Holy Spirit but not in your sense. If you would ask arians back then, they believed in it too. Tertullian also. Yet Tertullian could say that there was a time the Son was not. Now, the clearer and clearer thing looks like Newman oak tree. A rationalisation aposteriori of why one's theology is not found of old.
Is James asking whether first century Christians believed in the Trinity or whether first century Christians believed in the Nicene formulation of it? I think you are misrepresenting Tertullian somewhat. He was a lot more complicated than Arius, kinda like Origen's theology in a way.
Yes, it is true, Tertullian is complicated. In against Praxeas, he first says:
"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."
Wich is very trinitarian. But later he writes:
"For before all things God was alone— being in Himself and for Himself universe, and space, and all things. Moreover, He was alone, because there was nothing external to Him but Himself. Yet even not then was He alone; for He had with Him that which He possessed in Himself, that is to say, His own Reason. For God is rational, and Reason was first in Him; and so all things were from Himself. This Reason is His own Thought (or Consciousness) which the Greeks call λόγος, by which term we also designate Word or Discourse and therefore it is now usual with our people, owing to the mere simple interpretation of the term, to say that the Word was in the beginning with God; although it would be more suitable to regard Reason as the more ancient; because God had not Word from the beginning, but He had Reason even before the beginning; because also Word itself consists of Reason, which it thus proves to have been the prior existence as being its own substance."
Then comes a kind of reconciliation:
"Thus, in a certain sense, the word is a second person within you, through which in thinking you utter speech, and through which also, (by reciprocity of process,) in uttering speech you generate thought. The word is itself a different thing from yourself. Now how much more fully is all this transacted in God, whose image and likeness even you are regarded as being, inasmuch as He has reason within Himself even while He is silent, and involved in that Reason His Word! I may therefore without rashness first lay this down (as a fixed principle) that even then before the creation of the universe God was not alone, since He had within Himself both Reason, and, inherent in Reason, His Word, which He made second to Himself by agitating it within Himself."
But this is mainly mental gymnastic. And i won't even comment on "the word is a second person within you", wich would mean Jesus was 2 persons: himself and his word.
When you see the confusion of Tertullian, you can not recognize this in the NT.
Poll