The 'John Doe was dead' theory is BS
I've read it in a few places on this forum
"John Doe was dead and came back to life and that's why he knows everything".
This does not make sense. At the beginning, Doe says clearly that he doesn't know if there are little green men on Mars or anything of that nature. So he doesn't know *everything*, all he knows is stuff that other men could know. He has the knowledge of thousands of men, but nothing else. What "we" don't know, he don't know it either.
If he was previously dead and some God or "Higher Power" would have gave him "all the answers", he would obviously know stuff much more important about the Universe, Earth's origin and other similar stuff before knowing how many M&M's are in a pack of plain M&M's.
If it's true that the "came back from the dead" thing was in producers' mind, I'm glad that they didn't show that as an answer, that would have ruined the serie even more than the actual lack of ending.