Equinox:
The Roman church deveoloped the trinity idea between the years of 150 and 300 CE - this allowed them to fight the other Christianities.
Yes, and you could even say the idea resulted from such fights. By the time the Trinitarian creed was advanced church authorities had already tied the mselves to conflicting positions.
The Gnostics and others said Christ was truly God. It followed that, as such, he could only appear to be be human. Something omnipresent, omnipotent and immortal cannot at the same time be localized, vulnerable and mortal. Yeshua of Nazareth was thus a kind of apparition, a sort of holographic interface with creation by the Deity broadcasting the image.
In response the authorities took the position that, no, Christ really existed in the flesh. He was fully human.
The Arians agreed. They said Christ was fully human. From that they understood all declarations of his divinity and 'Son of God' status to refer to the level of godliness he manifested. His example showed that a person could live so righteously that God would grant them divine status. To elevate Christ to the level of God was to take one's reverence of Christ past the point of idolatry.
In response the authorities took the position that, no, Christ was eternal and divine before he was even born. He was fully God.
Once they worked themselves into that bind, the authorities were obliged to defend the logic of the positions they had taken. The Trinitarian doctrine offered a structure for defending conflicting points of view.
The sticking point for all the early Christianities was really monotheism. Had they not inherited monotheism as an imperative no problem would have existed. Christians were obligated by their Jewish origins and Hebrew canon to uphold the idea of one God even as they revered Christ. How then was one to understand the relationship of Yeshua of Nazareth to his God?
I'm glad to see you noting that the Gnostics and the Arians were devout Christians. They were indeed. And they took their monotheism seriously. Their teachings represented good-faith efforts to resolve a dilemma they had inherited from the Christians who came before them.
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Edited by Archer Opterix, : subtitle.
Edited by Archer Opterix, : corrected misspelling.
Archer
All species are transitional.