PZ Myers maintains his stance that you cannot convince him any God exists.
He's right, you know. Fundamentally, the sentence "God exists" is not literally meaningful, even in the loosest sense. It is a mistake, I think, to so easily concede that the statement "God exists" is literally meaningful. As Myers notes, to make the statement meaningful would entail a definition of God that most modern theists would find more objectionable than atheism, [UTA:] and we know of no such beings that actually exist. Alternatively, most atheists who blithely accept the meaning of this statement conflate "God" with "that which causes unexplained phenomena." But of course we are presently surrounded by unexplained phenomena, hence a vigorous and persistent scientific profession. If we sincerely believe that unexplained phenomena are by definition evidence of a god, we should all be theists.
Either way, I think the proper response to the question, "Do you believe any god exists?" is, "What the fuck do you mean by 'god'?" Furthermore, we should respond to the doubletalk and mumbo-jumbo spouted by theologians, apologists and the occasional philosopher with a similar question: what the fuck do you mean by "the ground of all being"? What the fuck do you mean by "that which we cannot speak positively about"? In general, "I'm entirely unimpressed that you can string a lot of fifty-cent words together in complex sentences; what the fuck are you talking about?"
The statement "God exists" is really a idiom for, "Do what I tell you to do, because you are a miserable, despicable sinner." Because I refuse under all conceivable circumstances to subordinate my own moral conscience to another's — all anyone can do is coerce my compliance, which requires guns, not gods — nothing can therefore convince me that any gods exist; the two statements are identical and I categorically reject both.
[Thanks to Dan for the update.]