Punish the Wicked (1970)

Eight teenagers arrive in a religious facility managed by Jacob and Sarow apparently to spend a couple of days practicing the principles of the Bible helping the elders and cleaning the place. Jacob and Sarow are very rigid in their application of the principle of the Bible, punishing the youngsters for minor infractions and demanding adequate clothing and behavior. When sinners vanish, the interns do not notice until a girl leans the truth.