The Rite is a 2011 supernatural horror-thriller film directed by Mikael Håfström and written by Michael Petroni. It is loosely based on Matt Baglio's book The Rite: The Making of a Modern Exorcist, which itself is based on real events as witnessed and recounted by American then-exorcist-in-training Father Gary Thomas and his experiences from being sent to Rome to be trained and work daily with veteran clergy of the practice. Wikipedia
Father Lucas Trevant: (from trailer) (Father Lucas shows Michael a possessed girl he is trying to perform an exorcism on) Father Lucas Trevant: What is it that you believe? Michael Kovak: That's not the devil. Father Lucas Trevant: Does a thief or a burglar turn on the lights while he's robbing your house? No. He prefers you to believe that he's not there... like the devil! Michael Kovak: Gets complicated when no proof of the devil is somehow proof of the devil.