Christian Presupposition in Harry Potter?

As the hub-bub about the final installment, (at least in writing), is coming to an end, this Jolly Friar ponders on some things Potter. Views on this subject are as polarized as the ice-caps and no shortage of opinion exists among Christian circles. So for the sake of stirring up the pot here at the abbey, I'd like to pose the question to all those who ponder.

Is there a difference between Tolkien, Lewis, and Rowlings? (Besides the obvious male/female distinction.) Are the Harry Potter series of books the same as "Lord of the Rings" or "The Chronicles of Narnia"?

For instance, the hero in the "Lord of the Rings" is Frodo Baggins, the humble hobit, with great character and self-sacrifice. Is there a reasonable parallel between Frodo and Harry? Gandalf uses magic and so does Harry. Is there a difference between them? Some say that Tolkien is fine, but Rowlings is not. Why? or Why not?

Some assert that the Potter books makes no sense, or could not have been written without a Christian presupposition. See Harry Potter Meets Cornelius Van Til Obviously using the Potter series as a spring board or opportunity to discuss the important matters of eternity is something that all Christians should be prepared to do. We must engage the culture and be able to intelligently speak about what is going on. I don't know how many times I've heard people comment on things they haven't read or seen. That is just ridiculous. If you haven't read something or seen it, you have no business commenting on it as though you know what your talking about.

This humble Friar believes that Christians may freely read Potter, but should always be discerning and understand what is truly Biblical and what is not. Children should indeed find an interest in reading, but if all they read is Harry Potter and nothing else, is that interest in reading a real benefit? I've known many who said their Children are reading more due to reading Harry Potter, but when you examine the content of what they read, there is little redeeming value in the content. In the final analysis, it's not Harry that's the problem in that scenario, the problem is much broader than this simple minded friar's opinion and well beyond the scope of "To Harry or not to Harry," that is the question.