As I wrote: to me, "a tree was Christian, never mind that tradition's questionable origins," by which I was referring to what you're referring.

Why is Christmas in December, anyway? Nothing in the Gospels says that; in fact, the implication is that Jesus was born elsewhen in the year. Many say the Christians appropriated the Roman Saturnalia. Even if that's true, it doesn't make Christmas any less Christian. Santa Claus, despite St. Nicholas, may be of pagan origin as well; again, that doesn't make him any less Christian now.