I agree with Geshtinnanna on this topic. It is fantasy novel writen for children to enjoy. Not to start a religious revolution.
It's fantasy for the sake of fantasy. Like people have mentioned earlier, three in no religion in the book, only the division between good and evil. It preensmany issues such as descrimination (also mentioned by others), and is a perfect way for such issuesto be addressed. fantasy. All children love fantasy and so it is something that they will more likely pick up and read.
Another valid point is that by being so opposed to something and being so outpoken on your disagreement with it is only going to give it a lot of free publicity. Just like the Da Vinci Code.
I guess my main point i wanted to make was that the book does not present paganism as a relgion at all. the magic in the book was not real magick at all. My favourite series of books (The Witches of Eileanan) are far more accurate in that it uses much of wicca and scottish witchcraft in the religion of te witches. It is also presented as a religion. Harry potter is purely a book intended for ejoyment, not shaping a pagan world.
And btw, witch is used throughout the book. the females are called witches, and yes it is in the name of the school. No offence but witch is used so frequently in the books that i'm surprised people thought the term wasn't used.