The Exorcist1973

Karras:
Look, I'm only against the possibility of doing your daughter more harm than good...I can't do it. I need evidence that the church would accept as signs of possession...like her speaking in a language she's never known or studied...Look, your daughter doesn't say she's a demon. She says she's the devil himself. Now if you've seen as many psychotics as I have, you realize that's the same thing as saying you're Napoleon Bonaparte. You asked me what I think is best for your daughter. Six months, under observation, in the best hospital you can find.

Chris:
You show me Regan's double, same face, same voice, everything. And I'd know it wasn't Regan. I'd know in my gut. I'm telling you that that thing upstairs isn't my daughter. Now I want you to tell me that you know for a fact that there's nothing wrong with my daughter except in her mind. YOU TELL ME YOU KNOW FOR A FACT THAT AN EXORCISM WOULDN'T DO ANY GOOD! YOU TELL ME THAT!