Harry Potter and God

Finally finished the last Harry Potter book. I have to say, I expected more elegant magic, interesting turns and solutions, other than a long drawn wand war, a lot of dead people and a predicable end. I'm not totally hating the book, but I had higher expectations...
Anyway, what astonished me a bit (and annoyed me), was the religious symbolism and wording which made it into Harry Potter. How does religion fit into the wizard world? I don't know, but religion can be made to fit into anything, I guess.
First thing I noticed were some goblins are talking: "God bless Harry Potter". It didn't help them too much anyway. Then Harry Potter meets Voldemort with his eyes down and wonders if he is praying. Where did this come from?? Then there is this whole scene which looks like a heaven or something close to it... Then somebody says: Thank god that you got your mother's brains.
Where does this all came from?
Several possibilities: No deeper thoughts, just what expressions Rowling grew up with.
Or: trying to please the average American reader. Or Rowling suddenly became more religious, or somebody close to her or to the book. Or she couldn't think of anything else (for the "heaven" scene).
Harry Potter and God, just doesn't make much sense to me!