I've been doing alot of reading about what was said by 2nd and 1st century "heretics" about what Christians thought and believed.
After the death of Alexander (the Great) Greek thinking, language, ethos and religious views were soaked up by all the conquered peoples.
The winner, after all, writes the rules and controls the history.
Judaism had undergone two major blows. First, the diaspora and the 200 year indoctrinations by Persian culture and religious thought. Then, the onslaught of pagan Greek culture, language, ethos and religion.
Jews now spoke and read only Greek by a large margin. Further, the success of Jewish culture had come at a price: absorbtion of pagan Greek ideas (mixed with Persian).
The Jews and other pagans who first heard the Jesus sayings (orally) would AUTOMATICALLY fit them into a pre-existing frame or context of thought which included the Pagan DEMI-GOD.
Philo, the Jewish philosopher, gave voice to the hybridization of Greek thinking and Jewish religion. He lived from 20 B.C.E. to 50 C.E.
Philo's works were enthusiastically received by the early Christians, some of whom saw in him a cryptic Christian. His concept of the LOGOS as God's creative principle apparently influenced early Christian theology. To him Logos was God's "blueprint for the world", a governing plan.
Romans were extremely tolerant of diversity among religions. In that ethos there was NO SUCH THING as DOCTRINAL ORTHODOXY.
If you worshipped a lesser god the greater god would not be thought jealous. Families of gods, after all, filled the pantheons. Roman religion was a cut and paste of Greek Religion with only name changes and superficial differences.
The average Roman thought Jews and Christians rude and boorish in not sharing their own Roman tolerance.
There were at first more Jewish Christians than Pagan Gentiles. But, with the destruction of Jerusalem and the spread of Pauls epistles the tide began to turn. A cultural pressure to be more Greco-Roman in Christianity gave way to a full blown definition of Jesus as not only a demi-god, but, a Triumvirate.
The modern day sense of the INDIVIDUAL apart from society and culture was a NON-thought. People survived by belonging to a corporate body, tribe, ethnicity and ritual belief system. In other words, as a person your sense of BEING was corporate (a nation: Roman, for example).
So, the eventual evolution of a fixed doctrine of a Corporate Deity with submerged individual identities was not a stretch by any means. It was a natural sequence of progressive concepts over time.
*edited to add: The Doctrine of the Trinity isn't true because it is an accurate description of Deity, but, because it was an accurate description of the thinking about Deity at the time BY THOSE with the power to defend that view using statecraft, enforcement and strong arm tactics.
There is, in my view, no such thing as an accurate description of God.