Christopher Hitchens, never missing an opportunity:
Most interesting of all, perhaps, and as noted by Orwell, “religion is also taboo.” The schoolchildren appear to know nothing of Christianity; in this latest novel Harry and even Hermione are ignorant of two well-known biblical verses encountered in a churchyard. That the main characters nonetheless have a strong moral code and a solid ethical commitment will be a mystery to some — like his holiness the pope and other clerical authorities who have denounced the series — while seeming unexceptionable to many others. As Hermione phrases it, sounding convincingly Kantian or even Russellian about something called the Resurrection Stone:
“How can I possibly prove it doesn’t exist? Do you expect me to get hold of — of all the pebbles in the world and test them? I mean, you could claim that anything’s real if the only basis for believing in it is that nobody’s proved it doesn’t exist.”
It's true that the Potter novels aren't an explicitly Christian fantasy in the same sense as the Narnia books (although Christian themes and motifs abound in Rowling's universe); what they assuredly are, though, is a series in which the central moral difference between the protagonist and the villain revolves around each's attitude toward his own mortality, and each's faith (or lack thereof) in the soul's survival after death. If Hitchens wishes to take this as an endorsement of atheistic materialism, by all means.
There is, of course, no organized religion to speak of in Lewis's land of Narnia either, and none of the Pevensie children seem to have received any religious education in their native England. (Which explains why none of them ever burst out: "By Jove, we seem to have wandered into the middle of a Christian allegory!") This was precisely the point: By purging his saga of explicit religiosity, Lewis famously remarked, he hoped to make his religious themes "appear in their real potency," and "steal past those watchful dragons" who rob the Christian message of its novelty and power. Whether Rowling had something similar in mind in her religiously-inflected saga I have no idea, but at the very least it's worth noting that the Resurrection Stone does in fact exist, Hermione's Hitchens-esque objections notwithstanding.