What would convince you that God exists?

This isn’t a new question, that’s for sure.  I’ve been asked it more times than I can recall, starting roughly ten years ago when I thought it would be fun to go online and argue at length with strangers about whether it makes sense to believe in God or not.  But apparently it has become a hot topic of conversation in the atheist blogosphere recently.  Let me explain.
No, there is too much. Let me sum up:

1. P.Z Myers wrote a post in response to something on the Richard Dawkins web site, saying that there is no evidence that could convince him of the existence of a god, mainly on the grounds that the concept is made so nebulous (by design, in his view) as to be indemonstrable.  And the only proper response to indemonstrable claims is unbelief. 
2. Jerry Coyne replied by suggesting a hypothetical scenario in which P.Z. encountered someone who could do really cool and mysterious things and goes by the name of Jesus. Would that convince him?
3. P.Z. responded to that by elaborating on his argument from incoherence.
4. Coyne then detailed the difference between intrinsic methodological naturalism (IMN) and provisional/pragmatic methodological naturalism (PMN).  Methodological naturalism is the term for what science does in refusing to invoke supernatural explanations for the phenomena it studies.  IMN, as he explains, is the “a priori philosophical commitment to not even consider supernatural explanations.” PMN, on the other hand, is an approach which does not automatically discount supernatural explanations, but basically says “I’ll believe it when I see it.”  A practitioner of PMN would not simply assert that ghosts, for example, can’t be studied scientifically, but would also not be willing to shut the door on inquiry and just accept truth claims about ghosts without investigation. Coyne said that IMN “appears to be the official position of the National Center for Science Education and the semi-official position of the American Association for the Advancement of Science and the National Academy of Sciences” and also P.Z. Myers, whereas Coyne himself agrees with PMN.  
5. Then yesterday Greta Christina weighed in on Coyne’s side of things, though she sees P.Z. as making some good points.  She asks: 1) if there is, or should be, anything which convinces atheists that they are mistaken about the non-existence of gods, and 2) if not, does that mean they are closed-minded and dogmatic?  She agrees with P.Z.’s argument from incoherence that religious believers do not have a clear and sturdy hypothesis, let alone evidence to support it, and do not generally make falsifiable claims.  She declares that “in order to persuade me that it was probably true, a religion would have to do more than just provide some decent evidence for its hypothesis. It would have to provide a decent hypothesis in the first place. It would have to provide a hypothesis that explains existing evidence, makes accurate predictions about future events, can be tested, can have those tests replicated, is consistent with what we already know (or provides a better explanation for it than existing theories), and is internally consistent. What’s more: This hypothesis would have to do more than just explain whatever new evidence might appear to support it. It would have to explain the utter lack of good supporting evidence in the past. It would have to explain why, in thousands and thousands and thousands of years of human history, supernatural explanations of unexplained phenomena have never once panned out…and a natural explanation has always, always, always turned out to be right.”  If a religion could do that, Greta Christina says, she would cease to be an atheist.   

Okay, there’s a lot going on there. There are multiple questions flying around in this conversation, and they deserve to be teased apart and addressed separately.  So:

Q: Is atheism falsifiable?
A:  Not unless by that question you mean “Is the existence of atheists falsifiable”?  Yes it is, and yes atheists exist.  But atheism itself is not a truth claim– it’s an epistemological position people take in relation to the proposition of at least one god existing.  All a person need do to be an atheist is be unconvinced of the existence of any gods.

Q: What is the appropriate view for naturalists to take of claims for the supernatural?
A:  I’m with Jerry Coyne on this one.  The statement that “science has nothing to say about the supernatural” is, so far as I can tell, either so obvious as to be tautological or so flimsy as to be like a Jenga tower contructed by toddlers.  Science studies the natural, and insofar as claims about “supernatural” entities are natural claims (praying cures cancer, for example), they are within the bounds of scientific inquiry.  As Greta Christina points out, every time science has investigated something claimed to be supernatural, it has revealed it to in fact be natural or non-existant.  The existence of ESP is something science can study, because it posits a falsifiable event– people reading the minds of others.  Even if the mechanism could not be verified just yet, a scientist can test whether it is actually possible to know exactly what someone is thinking without using cues from their behavior, your familiarity with their character, being told by someone else, and so on.  And if such a capacity were confirmed to exist, I can guarantee that scientists would not rest until they discover the mechanism, and furthermore that they would eventually find it.  And if scientists can find it, it is natural.

Q:  What would convince you that the supernatural exists?
A:  The answer to what would make me say “Wow, that’s really strange and amazing and I have no idea how it happened” is trivially easy.  Any number of magic tricks would accomplish the job.  But that hardly means those amazing events have no explanation, does it?   The only difference between a magic trick and “real” magic is the matter of how many people know what’s actually going on.  In the former case the at least the magician him/herself knows, and in the latter case he/she doesn’t.  Meditation wasn’t magic when even its practitioners didn’t know how it worked, and it isn’t now that we do know (at least somewhat).  Claiming that magic and/or the supernatural are things we cannot explain is simply begging the question– why can’t we explain them?  By what justification would you say “can’t” to mean “can’t ever” instead of “can’t just now”?  If we’re talking about an observable event, an event detectable in any way by humans, then the former position is thoroughly unscientific.  A scientist who looks at something strange and mind-boggling and says “We can’t ever explain that” has abdicated thinking like a scientist with regard to that thing.  Wearing the scientist hat means refusing to ever close the door on inquiry and hang a sign on it that says “Keep Out: Mystery Inside.”

Q: What would convince you that a god exists?
A: Nothing, and there is no conflict between that answer and what I’ve already said, nor does taking that position make me closed-minded.   “It could be aliens” is not at all a cop-out when it comes to that question, because it points to the ever-present problem that we have no way of distinguishing between that which is infinite and that which is really, really, really impressive.  Arthur C. Clarke’s law declaring that any sufficiently advanced technology is indistinguishable from magic could without any loss of significance be modified to say that any sufficiently advanced agency is indistinguishable from deity.  Finite beings cannot comprehend, much less confirm, the nature and existence of infinite beings.  I could be wrong about that, and if so by all means feel free to point out how.  But I’ve thought on this quite a lot and can find no way around it.  Could you convince me of the existence of aliens?  Yes, pretty easily.  But the gap between aliens and infinite beings is…..well, infinite.  “Almost infinite” is a nonsensical concept, and the frequency with which humans seem to forget this is a testament to our lack of imagination.  As is, for that matter, the tendency of humans to describe supernatural entities as thinking, behaving, and often looking uncannily similarly to humans.  The anthropologist Stewart Guthrie proposed decades ago that religion is essentially systematic, codified anthropomorphism.  I’m highly skeptical that it could be anything else.