Supernatural - Season 2, Episode 13, Houses of the Holy
Houses of the Holy
In Providence, Rhode Island, the local Gloria kills a man claiming that an angel in a beautiful white night had chosen her for redemption and asked her to stab the sinner to accomplish God's will. Dean and Sam investigate the case and they discover that other people had been visited by the angel and committed murders. Further, the angel has appeared after the death of Father Gregory, who was murdered on the steps of his church two months ago. When Sam is visited by the angel and asked to kill a man, the skeptical and atheist Dean confronts the faith of Sam telling that men cannot be angels and the light is an angry spirit indeed.