In my experience, you can tell a lot about a movement by how zealously obsessed it's followers are. No movement based on facts will ever be as loud as one based on lies. The subconscious knows when the conscious is not truly convinced, and that disconnect forces ideological overcompensation. Since these movements cannot survive scrutiny, they must be sustained by vigorous repetition, and brutal dehumanization of naysayers. Every conversation, every event, every single situation MUST be co-opted into the movement. Disbelievers MUST be forced to hear the broken record of lies, over and over again. It consumes and replaces their entire personality, and they are compelled by their ego to make sure everyone knows they are a good person, supporting the right cause. These people cannot be convinced by facts. They cannot be swayed by reason, because their entire identity is at stake. They have made sacrifices for the movement, lost friends, family, jobs, opportunities, etc. Adherence to the ideology MUST be absolute, because the flaws are so obvious, and so damaging, that any dissent must be purged and stamped out before doubt creeps in. Their mind will invent almost any explanation before it will accept they have been deceived, the cost is simply too great. A claim that can stand on its own does not need obsession keep it alive.