"How can you be sure you’re omnipotent? Perhaps you can accomplish anything you can imagine in your own corner of reality—a lucid dreamer can say that much—but there’s some greater reality you’re not even aware of in which, like the dreamer wakened, you’d have no such power. Or maybe even within reality as you know it, there are gaps in your power you aren’t aware of because you can’t even think of the relevant tests. The obvious response is that you’d know all these things because you’re omniscient—but of course, the same problem arises. How do you know you’re really omniscient? At most, there might not be any questions you’re aware of being unable to answer—but that’s hardly the same thing. The subjective feeling of omniscience might in fact be a symptom of a profound ignorance—being unaware even of the existence of those domains of knowledge you lack."
He wonders whether such a God might be able to offer us proof of his own omnipotence:
"It would require a good deal less than omnipotence to make a human perceptual system experience any demonstration of omnipotence you might care to suggest. So we might imagine God zipping you back to the dawn of creation so you can watch him summon all the galaxies into existence, then mold the earth and breathe life into the first humans, and so on. The trouble is that if you’re aiming for parsimony, the simpler explanation will almost certainly be that you’ve encountered a being capable of simulating all these experiences to your primate nervous system. That is, of course, a hell of a trick—a being who can do that is certainly pretty potent!—but still pretty far short of complete mastery over all space, time, and matter."I’ve always imagined the reasonable response to such an entity would be, “OK, so how does he do it? (or, possibly more interesting, why?)”. At which point we’re back to square one, trying to understand the science behind it all. It's one thing to levitate or turn water into wine. But how does it work? Or is the answer simply that "he can". Sounds to me a bit too much like a magician refusing to reveal his secrets.