Some theologians and apologists (notably, I gather, the fairly famous Alvin Plantinga) hold forth a curious epistemic argument purportedly in favour of their theism. The argument in one form (not due to Plantinga) goes like this: Evolution optimises organisms for survival and gene dispersal, not correct beliefs, which would be favoured only if they enhance the above.
That is, because there’s no telling whether unguided evolution would fashion our cognitive faculties to produce mostly true beliefs, atheists who believe the standard evolutionary story must reserve judgment about whether any of their beliefs produced by these faculties are true. This includes the belief in the evolutionary story. Believing in unguided evolution comes built in with its very own reason not to believe it.
Now, the most obvious problem with this argument is of course that evolutionary theory does give us a reason to suppose that we can arrive at true beliefs, because it is difficult to conceive of any process whereby a tendency toward mostly false beliefs would be beneficial for survival or gene dispersal. I'm sure some scenarios can be dreamed up where fortuitous misconceptions would cause an animal to behave in a manner just as good, or even better, as correctness, and certainly we know of (and science corrects for) some tendencies toward, for instance, false positive errors and other biases, but here we must imagine something both subtler and more pervasive, and in particular a mechanism that accepts sensible input from the exterior world and systematically transforms this input into beliefs that are erroneous and yet more advantageous than the simpler mechanism of apprehending reality…
Still, I don't think that's the argument's worst problem. After all, the assumption of some divine entity provides no more guarantee that your senses are accurate than a naturalistic view! On the contrary: Although it's not a logical proof, I think I have outlined a good reason to think that evolution is in fact likely to produce brains capable of apprehending reality, not perfectly but with at least some fidelity. Assume the existence of an all-powerful being, on the other hand, and that all goes out the window. What grounds have you to suppose, if such a being exists, that the beliefs it chooses to have your brain produce are correct? It is completely arbitrary! The apologist might conceivably argue that his God is a God of truth and so forth, but those are just more of the same arbitrary beliefs. On the assumption that an all-powerful being exists, which can manipulate your senses and beliefs as it sees fit, your are at the utter mercy of its intentions; and its intentions are unknowable, because it can make you believe whatever falsehood it wants, and every “evidence” you might have that your vision of this god is the right one is equally susceptible to (infallible) falsification.
Ultimately, both atheists and theists must assume some fidelity of their senses a priori, whether they wish to admit it or not. Although every epistemology needs its axioms, the naturalistic world view introduces no more than necessary, and people like Plantinga and his fellow admirers of the Argument from Arbitrariness (if you will) would do well to avoid casting stones in glass houses, for once you assume the existence of ultimate beings, everything is arbitrary.