Frailty (2001)

Frailty is a psychological thriller about a man named Fenton Meiks who tells an FBI agent that his brother Adam is the infamous "God's Hand" serial killer. As Fenton recounts the events from his childhood, it becomes clear that their father believed he received visions from God, commanding him to kill demons disguised as humans. Fenton and Adam assist their father in his mission, digging graves and burying the bodies of those they believe to be evil. The story takes a dark turn when Fenton realizes that his father's mission is not as righteous as he once thought, and he must make a difficult decision that will have lasting consequences.