It's important to note that in fact, most Muslims and many Christians (I don't know Judaism as well) believe that Moses, Mohammed, and Jesus were all true prophets. They differ in a few details, but the general message is the same.
I think it is definitely reasonable to address all of this evidence. One of Thomas Monson's predecessors expressly stated that he believed God truly did appear to Mohammed.
I never said I was necessarily skeptical of claims by Jews or Muslims. Some of them must have been brain glitches, just as some claims by Mormons probably are too. But I have no problem accepting that Jews, Muslims, and Christians (maybe even atheists) can all receive divine revelation.
As I said before, it's impractical to try to stretch this logic to argue in favor of any one religion. I'm talking about the existence of God in general.
FWIW, the form of Judaism I was raised in entails the assertion that Jesus Christ was not the Messiah, so is logically incompatible with most forms of Christianity.
That aside, though, I'm content to restrict our discussion to non-sectarian claims; thanks for clarifying that. I've tried to formalize this a little more in a different thread; probably best to let this thread drop here.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.