Signs of a Cult
While you can't judge all individuals by the group behavior, you can judge the group by the group averages. If there are traits in common to the group, that's hinting that it is a group dynamic. They might be filtering, intentionally or unintentionally. But either way, if you ride with outlaw bikers, don't be shocked if you end up in a bar fight.
(1) Tribalism: If there's differences in rules or treatment for insiders versus outsiders, that's a hint away from healthy group psyche.
(2) Hypocrisy: If the movement refuses to be introspective and admit it's own flaws or it's leaders don't live by their own rules, another hint.
(3) Ignorance: If the majority of the followers are low-information, prefer to argue feelings over facts, or fall back to talking points or fallacies like appeal to celebrity, authority, popularity? That's a hint.
(4) Intolerance: How do they respond to divergence of thought, identity or behavior, is one of the stronger indicators of whether it's a cult. Cults demand conformity.
(5) Transparency: How open is an organization, their finances or their leadership? Public versus private rituals or beliefs? A secret society and lack of transparency is cultish.
(6) Paranoia: Being paranoid and into conspiracies (especially doomsday ones), especially without some valid reasons, is a strong sign. So Jews or Mormons being a little paranoid has some valid history and justification, thus deserve a bit more leeway. Democrats in Academia or the Media? That deserves finger-ear orbits: the American Sign Language gesture for cult.
(7) Ability to leave: If adherents can leave, and not be ostracized or attacked? That's a good sign for a group. If they will be ostracized, maligned or attacked? It is not.
(8) Abuse: Demands for conformity, litmus tests for being devout enough, punishments for non-compliance with micro-managing norms? Cult, cult, cult.
(9) Insecurity: If adherents constantly try (and fail) to measure up to their exalted leader or absurd standards? Guilt, doubts, unworthiness are not signs of a healthy organization/individual psyche.
(10) Eccentricities A little is fine, a lot is not. Cults start differentiating themselves with alternate language/terminology, dress, mannerisms, or history. Those divergences from norms (and reality), aren't good signals.
(11) Prophets: If the leader is revered and infallible, and becoming more than a flawed human, then that's another strong hint of losing touch with reality.
(12) Extremism: a lot is about degrees and balances, which is what makes the lines a bit fuzzy. You can disagree, but how much? I once had a coworker shriek "No" in pain, like I'd physically struck her, because I'd mentioned some of the mis-assumptions people make on organic farming. Not a healthy reaction. But someone just politely saying, "I disagree and here's why" is completely reasonable. It's the old, "I'll know it when I see it".