Why ever not? What better way to glean the good lessons of good vs evil from the books, while assuring the kids that no, there is no such thing as magic? If you limit your kids to reading only what supports your and their worldview, how are they ever going to learn the tools to defend their beliefs when they leave home and go out into the big wide world?
The magic in the books is just a vehicle for the moral of the story, that good will win out over evil, and sometimes, folks have to pay a heavy price in order to do that which is good.
I read the last one before the kids got to it. ;o) I've really enjoyed the series, and it's fun to talk about the characters as though they are folks we know, and about the trials and triumphs. They are like any other fiction series in that regard; you come to 'know' the characters very well.
Plus, myself I've always figured that magic in fiction which is merely "mechanical" (point a wand, say some words, presto, ya got magic) is very, very different from magic that is based on connecting with a dark spiritual power of some sort.
Well said. I tried articulating the same, but you stated it much better.
I believe in God, but read Potter.