The Exorcist (1973)

Regan MacNeil: You're going to die up there.

Demon: Your mother sucks cocks in Hell, Karras, you faithless slime.

Demon: I'm not Regan.
Father Damien Karras: Well, then let's introduce ourselves. I'm Damien Karras.
Demon: And I'm the Devil. Now kindly undo these straps.
Father Damien Karras: If you're the Devil, why not make the straps disappear?
Demon: That's much too vulgar a display of power, Karras.

Demon: What an excellent day for an exorcism.
Father Damien Karras: You would like that?
Demon: Intensely.
Father Damien Karras: But wouldn't that drive you out of Regan?
Demon: It would bring us together.
Father Damien Karras: You and Regan?
Demon: You and us.

Father Damien Karras: There are no experts. You probably know as much about possession than most priests. Look, your daughter doesn't say she's a demon. She says she's the devil himself. And if you've seen as many psychotics as I have, you'd know it's like saying you're Napoleon Bonaparte.

Chris MacNeil: Would you like some bourbon in that, father?
Father Merrin: Well, my doctor says I shouldn't but thank God my will is weak.

Dr. Klein: Do you keep any drugs in your house?
Chris MacNeil: No, of course not, nothing like that.
Dr. Klein: Are you sure?
Chris MacNeil: Well, of course I'm sure. I'd tell you. Christ, I don't even smoke grass.

Father Damien Karras: I think it might be helpful if I gave you some background on the different personalities Regan has manifested. So far, I'd say there seem to be three. She's convinced...
Father Merrin: There is only one.

Psychiatrist: Is there someone inside you?
Regan MacNeil: Sometimes.
Psychiatrist: Who is it?
Regan MacNeil: I don't know.
Psychiatrist: Is it Captain Howdy?
Regan MacNeil: I don't know.
Psychiatrist: If I ask him to tell me, will you let him answer?
Regan MacNeil: No.
Psychiatrist: Why not?
Regan MacNeil: I'm afraid.

Demon: Your mother's in here, Karras. Would you like to leave a message? I'll see that she gets it.