No one can really know if there is a god or not and to claim with certainty there isn't is the same in my book as claiming with certainty there is.

I wonder who'd have the burden of proof.

It sems obvious those who claim he exists must have it because in all my existence and all the things I've learned, nobody has been able to show, demonstrate he existed. What does he look like, where does he live and also the countless different interpretations humans have of who, what he is show how weak that argument has become.
Most of those who don't believe in him aren't even concerned about him. He exists or he doesn't...So what?

But if he were not there, then two factors stand up: our responsability as humans and the laws of statistics (unfair things happen when we don't think they should and they always have an explanation). It makes life more difficult, but more interesting too.