Have you read the last book? That should dispel any notions that the series is "antichristian."
Actually I haven't read any of them. I read Tolkien and Lewis and found them to be excellent literature. I doubt that Rowling is in the same league with Lewis or Tolkien from a literary standpoint, but apparently her stories hold their audience interest, which is the principle goal of a professional author.
There is a lot of fundamentalist panic that goes into threads like this one. People somehow believe that if children are exposed to the idea of witches and warlocks and trolls and goblins that somehow their little minds will be so warped that God cannot restore them. Hogwash. Harry Potter may not be a Christian allegory, but in the end all allegories are what you, the reader, make of them.
Lewis admonished the Christian arts and literature community to stop settling for mediocre and to produce works of beauty and greatness and to instill within those works the values upon which Christianity is founded.
I suspect that Rowling has heeded that advice. People flock to read her books. The day the last book came out, I was at Target and a busload of teenage girls ran into the store (apparently still dripping from a swim meet), and gathered up every copy of that book that was still on the shelves. None of them flew in on brooms. None of them said a single expletive. Usually when you get a group of teenagers together they are all cursing and swearing and being mischeivous. These girls were all polite and not one of them had more than 1 tattoo.
Finally, brethren, whatsoever things are true, whatsoever things are honest, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good report; if there be any virtue, and if there be any praise, think on these things. (Philippians 4:8 KJV)