Well, I argue in "Must Atheists Prove there's No God?" that, indeed, the high, mathematical standard of proof is irrelevant in empirical matters. But that doesn't mean that some beliefs are "properly basic," or that they needn't be backed up by any evidence at all. As thinkers and intelligent creatures, we have some intellectual and epistemic responsibilities. Otherwise, how do we know we're not crazy and victims of a self-reinforcing delusion?
It's pretty convenient if a god doesn't feel like being tested, since that scenario would be consistent with that god's nonexistence. There are fraudsters out there who make similar excuses when their schemes come to light. No one wants to be exploited like that, so we have these reasonable expectations that we should justify what we say or do.
