Although Rowling draws on both Christian and mythological themes, the Potterverse isn’t a religious place. This much is well known. But what are we to make of passages like the following (book seven, pages 74 to 75):
“How do you feel, Georgie?” whispered Mrs. Weasley.
George’s fingers groped for the side of his head.
“Saintlike,” he murmured.
“What’s wrong with him?” croaked Fred, looking terrified. “Is his mind affected?”
“Saintlike,” repeated George, opening his eyes and looking up at his brother. “You see … I’m holy. Holey, Fred, geddit?
Mrs. Weasley sobbed harder than ever. Color flooded Fred’s pale face.
“Pathetic,” he told George. “Pathetic! With the whole wide world of ear-related humor before you, you go for holey?”
The reference is unintelligible unless you know a little about Christianity. George knows about saints, and he expects his audience to know about them, too. This passage is either evidence that wizards know more about Muggle culture than they usually seem to, or a rare instance of Rowling slipping up.