In the towns, at least at the top, there is something which does more closely approximate to the Islam of the learned theologians: an exclusive unitarianism with a hidden deity, which proscribes mediation, and so theoretically recognizes no clergy, and which preaches an ethic of rules rather than of loyalty. It neither expresses the cohesion of groups, nor provides an idiom of treachery.

Diego Gambetta, Trust - Making and Breaking…, loc. 2007