http://reason.com/archives/2010/11/30/t ... ment-punis
So why does religious priming induce committed believers to punish unfair behavior? The researchers suggest two possibilities. The first is that religious primes trigger the idea that one is being watched by the gods. “In this case primed participants punish unfair behaviors because they sense that not doing so will damage their standing in the eyes of a supernatural agent,” they speculate. The second hypothesis is that religious primes “activate cultural norms pertaining to fairness and its enforcement and occasion behavior consistent with those norms.” McKay and his colleagues acknowledge that religious primes might actually invoke both mechanisms. In either case, while the gods may punish uncooperative sinners, their work is considerably enhanced if believers go out of their way to punish sinners too.
Stuff I figured out decades ago.