The books are definitely shown from Harry's perspective, and certainly he would not have picked up any Christianity from the Dursleys, so I don't think Harry is religious at all. I don't think that means *none* of the characters are Christian, just that Harry doesn't particularly observe it if they are. In the graveyard, Harry doesn't recognize or understand the "last enemy to be destroyed is death" quote, but Hermione seems to, and even though she doesn't explicitly say it's from the New Testament she does explain that it means life after death. Certainly we don't see any gung-ho vocal Christians, and Harry would surely notice if, say, the Weasleys were weekly church-goers, but the reality is that most nominal 'Christians' are not particularly devout, either (especially in the UK, compared to the US).
Excellent points. You’re right about the unlikelihood of Harry’s having much contact with practicing Christians. Obviously someone in the fictional world goes to church, since they were having a Christmas Eve service in Godric’s Hollow when Harry and Hermione arrived there.
My sister-in-law is the daughter of a Church of England priest. I wonder what she thinks about the whole thing!
There's another Biblical quote in "Deathly Hallows." "For where your treasure is, there your heart will be also." That's from Matthew 6:19-24.
Now where's the "Harry Potter is the Devil" "Rowling is the Antichrist" crowd?