5.02 "Good God, Y'All"

Castiel tells Sam and Dean that he is going to search for God, who will be able to defeat Lucifer. Bobby's old hunter friend, Rufus, is panicked about demons attacking his town, and begs Bobby for help. Sam and Dean arrive at the town and realize there is a spell over the townspeople, making them hallucinate that they are demons and causing them to kill one another.