I call it a (wo…)manmade organised dogmatic religion. Sure, it might be just with a member of one (which is kinda cool and all and probably makes the organizing part a little bit easier) but it’s still kind of the same thing…

But seriously, it really depends on the details on such belief. It might be anything from harmless cope to superstition to delusion to paranoia. Or a first brave step in escaping a cult–which I would genuinely applaud.