Mainly, it refers to this world and the harsh reality in it. The bitter man is not really God, but people who handle politics and the representatives of government. In the beginning of the song and the end, there's even a little speech by a woman talking about the horrors she faced. It reminds me a lot of "Civil War" by Guns n Roses, where there's a speech too and the talk is about how governments make people turn into one another and the bitter man is the representative seen as a whole that brings unhappiness, pain and sorrow to societies. In any other world talks about the possibility of living somewhere else, where these things hopefully wouldn't exist.