The prayer comes from the 1999 cult film The Boondock Saints, written and directed by Troy Duffy. In the movie, Irish-American brothers Connor and Murphy MacManus recite it as a family prayer before killing mafia targets in Boston, framing their violence as divine justice. The film gained a devoted following on home video after a limited theatrical run, and the prayer became its most quoted passage, widely shared in fan edits, tattoos, posters and soundboards for its solemn, ritualistic tone.