I just have two thoughts: 1) of course there are Christian symbols and messages throughout the stories. That's been evident from the end of book one, and no, this is not why I read these books. 2) If a bunch of conservative Christian-Harry Haters start whistling a different tune in the near future, I will completely cease to care what they think on any topic. They've had their chance to give Harry & co. the green light. To wait until something raises up the Christian flag to love it is, even if we're talking about literature or ideas, incongruent with scripture. See Paul's actions in Acts 17(a chapter many evangelicals need to take another look at, I think), or maybe just give his admonishment to "test all things, hold to what is good"(1 Thess. 5) a try sometime.
A quick warning to readers, though: don't read this article if you've not finished the Potter series and are worried about spoilers. Not that I'm really afraid there are many such people left on the planet now, but there, I said it.