Therefore, there could be no doubts that Moses was a prophet, for not only did they all see and hear him receive the Law, and hear the ‘Voice’ he heard, but each one of them individually received the Law through prophetic communication as well, as a public body. BAZOOM! Proof.

This strikes me as really bizarre reasoning. A malevolent deity can fake one prophet's experience but is incapable of scaling the deception up to convincing everyone personally?

ETA:

Within Judaism, matters that are treated as being incapable of being fully comprehended by the mind are always, exclusively, of an existential nature. The essence of G-d, the nature of the soul, free will, the nature of good and evil, etc., are all treated as being incapable of being fully understood, and these are all existential concerns...

And what happens if we figure out, say, free will or the nature of good and evil? Would that cause you to modify your opinion?

First, it is only inevitable that ontological reductionism leads to ethical and existential nihilism.

You say this like it would be a bad thing if true. I think your mental model of what/how atheists think is not very accurate. What's so is so, whether we like it or not (see the obligatory http://wiki.lesswrong.com/wiki/Litany_of_Gendlin and http://wiki.lesswrong.com/wiki/Litany_of_Tarski). Reasoning from "nihilism is bad" to "therefore, reductionism is incorrect" is not a reasoning method which will reliably lead you to correct conclusions (argument from consequences).

Also, the formatting on this is inconsistent.