Why Is Christmas on December 25th? | Dr. Tom Schmidt

This is the point where magicism and literalism consolidated in the life of the Church. Where form became more important than truth and where forgiveness had to be blessed rather than mutually given. Adam and Eve went from being Jewish myth about the nature of blame and knowledge of evil being corrosive to now being historical. This gave power to the hierarchy - making it part of the ruling class - eventually taking it over. 

As far as the trope about Christianity copying Greco-Romanism, the opposite is true. Greco-Roman culture migrated from Carthage, which was brought there by Phoenicians from the Levant - including the myth of a Messiah who would restore man to fellowship with God. Kronos came from El, not the other way around.