What a bunch of Barbara Streisand, as Rush Limbaugh is often wont to say. People are forgetting that the Harry Potter books are works of fiction, for gosh sakes!
Having read the books myself, there is NOTHING in these books to seriously contradict Christianity per se. After all, note that at Hogwarts they do celebrate Christmas and Easter very clearly.
The phrase get a collective life definitely applies to too many Harry Potter detractors, IMHO.
That's one of the problems I have with the series. The HP world is not a little world drawn from the imagination that exists outside of our world. The celebration of Christmas and Easter presume that Christianity is around, yet HP is all about witchcraft (albeit cute little witches flying around on brooms). The bible (ya' know......the idea behind Christmas and Easter?) clearly forbids witchcraft.