HP books/movies, while also have some values that Christians don't agree, were not written intentionally to undermine Christianity.
Suppose Osama Bin Laden is a good author, and he writes a very good fiction with a very anti-American message. I just don't see why any American (except the rabid leftist) want spend their money on a movie based on that book.
But oddly, the reaction to this movie seems tamer. To date I haven't seen any protests burning these books.
Maybe this is a sign of more tactful strategy on behalf of Christians since the Harry Potter protests seem to have little effect.