Instead of writing an elaborately referenced reply to andrewla, I decided to mention that the current term people are using is "high-demand groups" because to monotheists, part of the "cult" definition is tied up in the deviation from their religion.

If we're talking about extremely insular, high-commitment groups that tend to punish people who leave, we might as well leave behind a word that is just as often used by monotheists to refer to heretics. "Cult" and "occult" are from "hidden" anyway, as in you'd better hide if you're a heretic.