Mainstream Christianity has always appropriated other cultures in its imperial ventures. That's how it attempted to be all things to all people. The Church demonized the parts of pagan cultures it didn't like, and assimilated the rest, demoting foreign gods to saints or angels.

There's a conspiracy theory that the Romans wrote the gospels to tame Judaism or to use Christianity as a Romanized version of Judaism for propaganda, to unite the empire. A more realistic scenario that comes to the same thing is that the early Christians were inspired by both Judaism and Greco-Roman religion and philosophy, and had to tone down or spiritualize Judaism after the Jewish-Roman wars destroyed Jerusalem, to placate Roman expectations.