I can't argue against the valid points you've made, but those who inherited the good news of the mystery of God revealing himself to the world annexed that holiday celebrated by Europeans and turned it into a time to celebrate Christ's birth on Earth. The origin of a holiday =/= what the holiday means at a later points =/= what it means today. All that said, I also subscribe to the theory that Pagan religions, though corrupted, also trace their roots back to pre-messianic times when God revealed himself in different ways. Odin could have been Japheth for all we know.