Evil against evil.
Foreshadowing. The opening of the film takes place at an archaeological dig in Iraq where something that has been uncovered is clearly deeply disturbing to Father Merrin. The film wisely avoids over-explaining the significance or history of any of this section, but the evil against evil line definitely helps to create a sense of dread that pervades throughout the rest of the film.
Good morning Karl. Oh Karl, we've got rats in the attic you better get some traps.
The setting has moved from the dusty desert of Iraq to the comfort of an affluent townhouse in Georgetown in Washington, DC. Before the viewer has a chance to know much of anything else, it is informed that there is something wrong with this picture. This is an upper middle class household and the idea of there being a rat problem in such a nice home doesn’t seem obviously out of place until more is learned. It is a subliminal suggestion that there is something off here, but it is not presented in an obvious way. And, of course, it turns out that the problem isn't rats at all.
Captain Howdy, Do you think my mom's pretty? Captain Howdy? Captain Howdy that isn't very nice.
Another clue that something is off in this house is the sudden manifestation of Regan apparently having an invisible friend. She describes Captain Howdy as the mysterious invisible character that answers the questions she had been posing using a newfound Ouija Board. That Captain Howdy apparently says something derogatory about Regan’s mother also seems off as up to this point the film has presented their relationship as probably better than average.
Ya know, those things to get attention, like saying that her bed shakes and stuff.
Chris in the doctor’s office and the viewer now learns that Regan has been brought in for examination and is perhaps in need of a psychiatrist. The movement from something being merely “off” in the Georgetown townhouse to something being specifically off now begins to come into focus. And yet even the discussion of a depression, and Regan being given Ritalin and the potential for needing to see a psychiatrist does not seem to fit in with what Chris has termed her daughter’s “lies.”
The shaking of the bed, that's doubtless due to muscular spasms.
Later, after the audience finally has been made witness to some of the behavior which warrants Regan needing serious medical help, the same physician is still sticking to the same diagnosis. By now, Chris is no longer convinced and completely dismisses the medical help or lack thereof her daughter has been receiving.
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.
Giving up hope on medicine to cure her daughter’s increasingly bizarre behavior, Chris has taken the advice of seeking out help from religion. Father Karras is not just a priest, but also a mental health professional and after his initial interview with Regan he remains unconvinced that her problem is spiritual.
We may ask what is relevant but anything beyond that is dangerous. He is a liar. The demon is a liar. He will lie to confuse us. But he will also mix lies with the truth to attack us.
Eventually, of course, the real problem with Regan is made clear and medical care is tossed out the window (so to speak) in favor of a spiritual treatment. Merrin has experience in exorcism, but Father Karras does not so he is careful to instruct the younger priest on what to expect.
“Your mother's in here, Karras. Would you like to leave a message? I'll see that she gets it.”
As if to prove Merrin’s point, the Demon inside Regan tries to manipulate the Father Karras who is wracked with guilt over not being able to take care of elderly mother like he wants and believes he should. The Demon even speaks to Father Karras in his mother’s voice in an attempt to undermine the priest’s already rocky faith.
She doesn’t remember a thing.
The demon exorcised from Regan's body, both exorcists dead and the ordeal over, mother and daughter are leaving the rented townhouse in Georgetown under the best possible terms.
