Violent people often claim that God sanctions their actions. In two studies, participants read a violent passage said to come from either the Bible or an ancient scroll. For half the participants, the passage said that God sanctioned the violence. Next, participants competed with an ostensible partner on a task in which the winner could blast the loser with loud noise through headphones (the aggression measure). Study 1 involved Brigham Young University students; 99% believed in God and in the Bible. Study 2 involved Vrije Universiteit-Amsterdam students; 50% believed in God, and 27% believed in the Bible. In Study 1, aggression increased when the passage was from the Bible or mentioned God. In Study 2, aggression increased when the passage mentioned God, especially among participants who believed in God and in the Bible. These results suggest that scriptural violence sanctioned by God can increase aggression, especially in believers.