Interesting theory, and perhaps one that's got legs, but there's some self-reinforcement going on in the religious sphere that keeps it from being unicausal -- if we've got a religion whose vision of God (or of a god of rulership like Odin or Jupiter, or of a divine hierarchy) is initially a simple reflection of how its members want to be governed, I'd nonetheless expect that to drift over time to variants which are more memorable or more flattering to adherents or more conducive to ingroup cohesion, not just to those which reflect changing mores of rulership. Then group identity effects will push those changes into adherents' models of proper rulership, and a nice little feedback loop takes shape.

This probably helps explain some of the more blatantly maladaptive aspects of religious law we know about, although I imagine costly signaling plays an important role too.