Years ago, I was IMing with a friend who was a devout born-again Christian. He said that he knew God existed because when he had been tutoring some local underprivileged kids, he felt sure that those kids' academic improvements were, at least in some cases, due to God's touch. To him, it was evidence this was a world that had God in it.

I didn't think to ask this at the time, but I wish I had:

How do you tell the difference between a world where God exists, and one where he doesn't?  ¶ 23:29