NOT A PLOT HOLE: I see people saying this movie has plot holes because where did they get food and where are bodies?

yep

Humans cannot subsist on cannibalism. It takes calories to raise a woman to child-bearing age. There could not be enough of an incest population to sustain the population for a cult. Also, human food must remain reasonably fresh to be healthily consumable. They would have to kill too many outside victims for cannibalism to work without coming under suspicion. And lets not even consider the diseases that would be transferred from uncooked random humans after consumption.