A couple of years ago I wrote this little brief history of Christmas which showed how the holiday was derived from Pagan traditions and had little to do with Jesus. If you have not yet read it, take a look.
I was prompted to bring it up because I saw this video (H/T Hemant Mehta) just now and it touches a lot of the same points (Although my post covers more).
So, merry whatever everyone!
Skepticism, Properly Applied 