Well any religion can be seen as a sort of philosophy so the argument of whether its a religion or a philosophy is kind of silly. It can be both and is both.
As far as the Christmas thing, Im about as non-religious as you can get, but I dont personally see the issue with publicly acknowledging Christmas and even the whole nativity thing. To me, that story and the holiday in general transcend religious beliefs and have become cultural. I think if you are offended by a nativity scene or any other Christmas decorations youre trying too hard to be offended. Its just as much a part of our culture as it is a part of a religion. The time spent complaining about Christmas decorations would be better spent on church/state issues that are actually issues.
We completely agree on something. Careful, you'll hurt your "street cred" if you agree wtih me too many times. :-)