It's not even "GIGO" with these people. "Garbage In, Garbage Out" implies that the process between input and output is legitimate at least. They're not trying to make justifiable decisions in the face of incomplete information, or detect inconsistencies among their own beliefs, or anything of the sort. They're just emitting math-shaped noises to bolster their own egos and further insulate their cult. They use language nominally about changing one's beliefs in order to keep their own beliefs locked in place.