The secret is that there is no god- man is his own god and can BUILD his own reality.
The ones that BUILD are the gods among men.
By trying to make sure everyone else, including all but the highest levels of their own members, believes in some external force to save/condemn/judge they, they ensure that all the REAL power on earth stays in their hands.
They aren't bound by the limitations of "good" or "evil".
I could be wrong though.