Interesting take on monotheism, really. Bit like all those James Bonds all supposed to be the same character. At least in Doctor Who there's an in-universe explanation for that sort of thing.
At the age of five, Skagra decided emphatically that God did not exist. This revelation tends to make most people in the universe who have it react in one of two ways - with relief or with despair. Only Skagra responded to it by thinking, 'Wait a second. That means there's a situation vacant.'