As for stepping away from the core Christian Teachings as...

As for stepping away from the core Christian Teachings as espoused by Christ and James, Peter moved the goal posts a bit and Paul moved them away altogether. So Christianity began to unravel in the first generation of Christians.

As for the CC and their version, I doubt they formed an opinion with ill intent. It may have been to appease Constantine to some degree. And I'm sure they had no idea of the consequences of the claim that God was some kind of Triune God, thus elevating Jesus to be a integrated part of God and thus God Himself.

This had disastrous consequences for people in Third World countries and other religions. That said, you believe that Jesus is the only path to God so even though you reject Jesus as God, for all intents and purposes it makes no difference in your life. You still reject the religious beliefs of all non-Christians just as the Trinity believers do. So your difference is no difference at all.