An interesting working paper by the University of Connecticut economists Metin Cosgel and Thomas Miceli looks at a dataset of over 300 governments between 3,700 BC and the 20th century in order to “identify the factors favoring the emergence of theocracy.”
They found that “theocracy is more likely to emerge in those polities where (i) religion is able to serve a legitimizing function vis-à-vis the state, (ii) the religion market is monopolized, and (iii) the dominant religion is monotheistic.”
So what is it about monotheism that encourages religious and political authorities to merge?
An increase in the number of gods (a move toward polytheism) is like entry of religious providers in the sense that it will reduce the ability of religion to legitimize the state. Specifically, because a polytheistic religion has multiple gods, the populace will be divided in their loyalties (as they were with multiple religions), thereby diluting the power of any one god (and by extension, that god’s secular representatives) to confer legitimacy on the state. In contrast, a monotheistic religion requires worship of a single god whose power to legitimize the ruler is necessarily more concentrated.
It also seems like the benefits would go both ways. If monotheism helps political leaders gain legitimacy, these political authorities also help spread monotheistic faiths like Christianity and Islam through conversion and conquest.
Via Branko Milanovic