Demon: What an excellent day for an exorcism.
Fr Karras: You would like that?
Fr Karras: But wouldn’t that drive you out of Regan?
Demon: It would bring us together.
Fr Karras: You and Regan?
Demon: You and us.
The most chilling exchange in the movie. Particularly if you’re familiar with how it ends.
The lede image to this post is the inspiration for the scene of Fr. Merrin arriving at the house, René Magritte - The Empire of Light, II: