I wanted to conclude Harry Potter month by making some observations about the Harry Potter series and its Christian content.
One of the amazing and unique aspects of the Harry Potter series is how the novels change with Harry and his friends. The series begins with a ten-year-old Harry who is innocent and in many ways ignorant (in the best sense of the word) and ends with a mature seventeen-year-old Harry who is knowledgeable of the ways of the world without being influenced by what he knows, as Christians are called to be ("wily as a serpent, innocent as a dove"), and knowledgeable about greater truths such as love and sacrifice. Rowling's writing style changes and develops with Harry, as does the structure of the books. As Harry grows, the novels become longer and more mature in content. They begin as relatively simple school stories with a few interesting twists (magic, Voldemort's lurking presence) and end as complex, mature stories of the true nature of reality and of the struggle of good versus evil, with a sensible progression from one extreme to the other.
Rowling's writing style changes as Harry does. She improves tremendously as a writer through the series, becoming much less dependent on simply telling the reader what each character appears to be feeling (although this style worked extremely well for the more satirical nature of the earlier books). She tells the reader outright less and less what Harry and his friends are feeling, with the result that it is easier and easier to sympathize with their feelings, become engaged in them, and feel their emotions yourself. As Harry and his readers mature, Rowling also moves away from simply satirizing human nature to attempting to understand why characters behave the way they do. In earlier books, the Dursleys, the Malfoys, Snape, and others are portrayed simply as hilariously awful people whose antics are entertaining; by later books, the motives of these characters have been discovered and explored. While this of course does not excuse their abhorrent behavior, it does create a certain amount of compassion for what they have gone through and why they have become the people they have become.
Something that Rowling does strongly throughout the series has to do with the morals of her stories. These morals are rarely verbalized (and normally by Dumbledore); rather, the reader is left to infer for him- or herself that it is wrong to bully, oppress, torture, hate, and so on. Prejudice and oppression are strongly condemned through despised characters such as Dolores Umbridge, as well as through acquaintance with those who are oppressed even before Voldemort returns, such as Remus Lupin, Rubeus Hagrid, Dobby, Kreacher, and perhaps even Hermione. Hagrid especially may not have had much formal schooling, but he has a huge heart that is in the right place. He is always determined to see the best in everyone and every creature (no matter how spiny, scaly, toothy, hairy, or blood-thirsty), so trusting and generous with his time, and so determined to do what he wants no matter what others think in a way that is so reminiscent of God and His best warriors here on earth. Judgments based on worldly values such as appearance or societal status are invariably wrong. This rule (show rather than tell) applies to Harry's behavior as well; he often makes bad choices that are not outright condemned, but often these behaviors are subtly punished. They are not always punished, however, and sometimes his morally wrong choices are portrayed as 'right given the situation'--a weakness of the series.
Another strength of the series, which I have touched on before, is how well Rowling builds the wizarding world around us through the years. She includes incredible amounts of detail throughout the books about both the world itself and its characters, details that weren't strictly necessary but make the world much richer and easier to imagine. She also includes an incredible amount of detail that is mentioned briefly but ends up being important later (this especially comes together in Deathly Hallows), and the amount of plotting that must have gone on before writing began is impressive.
Magic per se may not be Christian, but the Harry Potter series is. It's full of Christian symbols and symbolism, such as phoenixes and unicorns and symbolic (or actual) deaths and resurrections. Harry always receives help in his final battles--he is never able to achieve anything alone. Only with help (always from either Dumbledore or a proxy of Dumbledore) is Harry able to survive and succeed, and he is only ever able to reach the end of the book well-prepared through the help of friends. It's a wonderful representation of the Church and Christian life--no one can prevail against sin without help from both God and others.
Finally, I would like to point out how impressive a feat the Harry Potter series is. I love almost every character, and I cry every time I read Deathly Hallows--something I can say of no other book or movie. I cannot recommend this series enough, perhaps especially to Christians.