The Oldest Trick: The Exorcist (1973)
William Friedkin’s 1973 film, adapted from William Peter Blatty’s novel, takes that logic and dismantles it. The Exorcist is a film about a demon who operates through misdirection, feeding medicine, psychiatry, linguistics, and the Church just enough to keep each one looking the wrong way, while saving his most devastating instrument for the one man in the room who is already halfway destroyed.