“I was always told that Christians believe in 3 gods, both by other Jews & Muslims.”
That’s a nasty slander, rejected by no less than the “RamBam.”
Not sure I understand the trinity concept, but it’s like water, ice, and vapor -— more or less the same thing, different aspects.
I am Christian, and I have no doubt the one and only God, my Lord, is the God of Abraham, Issac, and Jacob.
Maimuni said that Christians are idolators. But Islam & Christianity serve HaShem’s purpose in bringing the gentiles closer to the true religion that will culiminate in the times of Moshiah.
I never learned much about Christianity, so I won’t argue details of the religion with you. My world consisted only of Jews & Muslims.