About this "split" again: I found a way how it could be done.

If history can be played out in such a way, that at the point of separation (allegedly 21th Dec 2012) the two sets of people ( those destined to "hell" vs. those destined to "heaven" ) are disjoint, then nobody will notice that the one world divided into two and these two departed from each other.

This can be done by ensuring that as we get closer and closer to the point of separation, we lose all contact with those people who belong to the other group. At the moment of separation, the only thing that remains of those other people are memories, which may - again, by design and careful orchestration - never provide enough impetus to begin a search for these "forgotten" people.

This way, a large part of the world can be "cut away", without anyone noticing anything.