My own theory is a bit different than others. I think there are certain places that are similar to heaven and hell, but they aren't heaven or hell and only referred to such because of mainstream belief.

Now, I'm not sure what they are called or who runs them, but I believe that there are dimensions based upon this one universe. Not parallel universes, but different versions of the one universe upon three or maybe even a greater number of dimensions. The ones we would be very familiar with are our own reality, a heavenly dimension, and a hellish dimension.

It's just something I put together long ago to create a theory to the things I have seen, what my friends have seen, and just how life is much more than based on universal laws.