What proof would exist to say that they are who they say are?

Also, magicians can produce things like people floating, hovering, etc. and there is no conceivable flying apparatus.

As for the mountain moving, you didn’t say that a volcano couldn’t errupt coincidentally with the appearance of this person. Or a lava dome collapse. Or an earthquake. Or a sink hole.

I’ve learned (only recently to my discredit) that part of critical thinking is always coming up with alternate hypotheses to explain something. The example I gave—I meant for the person to descend from a stratospheric altitude, by the way, to make an illusionist’s trick unlikely—could be explained by a manifestation of God, or as you suggest it could just be a very talented magician and a very handy coincidence. Or perhaps it could be an alien capitalizing on human religious traditions. In this case, I think the first would be most likely hypothesis.

I would probably also accept less dramatic evidence like the spontaneous regeneration of a major limb by people who were prayed for. (Did you know that children under the age of eleven can regenerate their fingertips?)

John,

I too doubt that anyone could present conclusive evidence that they are God, but if someone moves a mountain and then demands worship, I agree that the prudent course would be to comply.

Personally, I’d settle for a far less convincing display. A reasonably impressive mystical experience of any kind (and not the low-bar warm fuzzy of Mormonism) would probably be enough for me to believe. On the other hand, I don’t really mean that it would be enough to objectively convince me that such a being existed. But it would be practically enough to spur me to self-conscious religious expression and subjective belief.