What gives a religion the right to claim their fantasy is correct and the rest false?

[robvalue]

I wonder if Christianity will ever get past the first book.

"Oh look, a story about a talking snake and the Earth being magicked into being out of nowhere."

Christian 1: "Well, obviously, it's metaphorical. You'd have to be an idiot to think that literally happened."

Christian 2: "Well, obviously, it happened exactly as written. You'd have to be an idiot to doubt the word of God."

So... did any of them get round to asking God? You think he'd have cleared this up by now.