It would be kind of interesting to write a book with the same premise as the Left Behind books, but done a lot more realistically. Who would actually disappear? What are the demographics of born-again Christians? (Lots of long-distance truckers? Not so many accountants?) What do the Gospels really say about who's going and who's staying? And what would the psychological consequences be for the people who were, in fact, left behind? What happens to humanity when the question of whether there's a god, and whether there's one true religion, is answered - and you find out you were wrong all along?
I don't think that I could write this book, unfortunately, because I feel so bitterly toward religious fundamentalism that I don't think I could be sympathetic. But you know, someone should.