"Generally I find the best explanation to why She does anything is that it is ineffable. But, in this case, She created literal darkness, as in the darkness that exists in the absence of light, not the metaphorical kind," he said, then amended, "Though She created that as well, I suppose. Lucifer had been an angel--that's what we call the divine beings She made to help Her--before his Fall. He and some of his followers didn't like that the humans had been given dominion over Earth, or they questioned Her Plan too much, so they rebelled and were cast out."