For the same reason you might like Lamb: 20,000,000 coyotes can't be wrong.
All kidding aside, there can be no empirical evidence within the closed circuit of the universe. God is not inside - but is outside...and you can't go outside to prove it to yourself.
It is as if we were all born into a large room that no one had ever been or seen outside of, making no expert knowledge possible by those who could not possible confirm anything. Under those circumstances, the only way that it would even be possible to know the truth - is if the information came in...from the outside. But...if you were the guy who received the note that was passed under the door...everyone else would call you crazy. And if there was another person every so often down through history that received a similar message...and they began to write it down and put it in a book...and they called it their "bible" - that would just be crazy...2,000,000 coyote crazy!