Hot dang, “Tubular Bells” is one of the greatest horror themes of all time, isn’t it?

Pazuzu, a dastardly demon, possesses young upper-class girl Regan (Linda Blair) and makes her say mean things, spew blood, get all gross-looking. Her mother, Chris (Ellen Burstyn), enlists all sorts of experts to explain her daughter’s condition, but none of them manages to do so.

Father Karras (Jason Miller), a priest with doubts due to his own mother’s impending death, is brought to help perform an exorcism on her. Karras is joined by Father Merrin (Max von Sydow), who has history with Pazuzu. Can they save Regan from Pazuzu’s grasp? When you stare into the heart of evil, will your faith in God guide you to salvation?

No movie on my list this month has quite the legend attached to it as “The Exorcist.” In fact, I grew up afraid of it more than just about any other. My parents always told me it was one of the most terrifying films ever made. I listened to “Tubular Bells” frequently. When I was very young, I avoided even looking at the cover art. Maybe that and “Tubular Bells” are why I assumed “The Exorcist” was classy.

“The Exorcist” is not classy. It is a raw, weird, unencumbered, shock schlock.

At first I feared it would feel dated because of Christianity’s central role in the movie. That isn’t to say openly sacrilegious screeds are widely accepted in popular culture, but stuff like “Go suck Satan’s cock in hell” is “South Park” material and using a crucifix as a sex toy is pretty tame, all things considered.

I was prepared to say, “Christianity is an implicit cultural assumption in 1970s American cinema, just as it is now usually ignored or used materially in contemporary popular culture …” I would have been wrong, but not for Christianity’s sake. Father Karras is a compelling character because he enters into the situation a man of flailing faith. His staredown with Pazuzu proves his mettle. It’s a universal theme in horror and it still resonates.

What I did not know walking into “The Exorcist” is that it is hard to watch because it is essentially all about child defilement. The aforementioned crucifix scene is something you can see elsewhere but not with a child doing it. Regan’s physical deformation and awfulness is something many movies since have copied, but rarely to this extent or at least with such mainstream notoriety. It is genuinely disturbing. I say “The Exorcist” is shock schlock because it feels distinctly so, a symphony of nastiness with full crescendo of fucked-up green-bile madness. It goes places not just religiously, but physically and morally, and for that it remains deeply unpleasant.