The terrible behavior of the god-believers is a convincing evidence of the non-existence of a morally influential God. Believers loudly legislate each others' behavior, imposing their made-up gods' made-up codes on each other (and the rest of us). And believers in gods constantly embarrass the hell out of each other.
It's a shame there isn't a real god behind all of the shouting, the offense-taking, the in-the-name-of-killings, whippings, wars, and blasphemy laws, sitting up above it all, shaking his divine head in disgust. The way the world is going, we could really use a god.