I agree with you brother, but I have looked a bit into the matter, and possibly the only Christian thing about Christmas is exactly Santa Claus.
What I mean is, he was a good pope (and then of course we can discuss whether a pope can be a real Christian according to his religious conviction, according to church history, I am sure the first ones were). Anyway he was a good pope and he was and is a giver, and (not to forget) he makes people happy. That's about all the Christian thing you find about Christmas.
But Gerani, lets get back to you. Can you provide the actual sources which prove that Christianity has been influenced by this paganism you refer to?