[Serious] Could an omnipotent and omniscient god prove that he was God?

[Neo-Scholastic]

I think Rand took as axiomatic that we're not brains in jars and reality isn't virtual, that's what she meant by 'existence exists'. I can't prove she's wrong or right about that, but there doesn't seem much practical use in acting as though existence doesn't exist.

I believe, Ayn Rand, as a materialist was actually more concerned about Kant and German Idealism. But appart from her scorn and her unwarranted elevating of the statement "Existence exists," as one of her axioms, she did not grapple with any real ontological problems in her writings.