CurtC
Illuminator
The answer could be found studying the mindset of the people who made up this particular version of a god.
I think it's deeper than that. Throughout history, many different concepts of God have been dreamed up, and the ones we're left with today are the versions that could propagate themselves. It's like biological evolution - try everything and keep what works, although in this case religion "works" for itself, but to the detriment of its hosts (us).
Darrell Ray has written a book called The God Virus, in which he talks about how religions use guilt to trap people. They take something that people are going to do anyway (masturbation, pre-marital sex, etc.), and tell them they're not supposed to do those things. This causes guilt when the people inevitably do them, and the religion then sets itself up as the way to absolve you of this false guilt.
This strategy has worked really well to propagate religion.