The more I think about it, the more I find it ridiculous that people will even argue for the existence of an invisible being for which there is no evidence. The fact that they have to argue about the existence of a being that is supposed to be all-powerful should be enough. Anything that exists should be able to be observed. The fact that he never shows up to defend himself says a lot, I think.
I know that philosophically, this is a fallacious argument and wouldn't stand up to rhetoric, but it does seem absurd to me that people don't see how starkly plain it is that God probably does not exist. For all the arguments, whether cosmological, ontological, or any of the thousands of straw men and ad ignorantium arguments, the debate can really be reduced to:
Theist: "There is a God."
Non-theist: "Where?"
Theist: "He's invisible."
Non-theist: "Then it doesn't really matter if you are right or not."
The end.