I've seen a handful of older movies over the years that have a reputation of being scary or shocking, but have lost their impact over time, either because of poorly aged special effects and make up or changes in societies taboos. For example, Hellraiser and parts from The Apple, where they lean into then little known BDSM and queer culture to shock and titillate the audience. However, The Devils would still 100% be shocking if shown to modern audiences. I do think it's an interesting watch, if only for the spectacle of it all.
Content warning after the jump for sex and assault. Also spoilers I guess!
I watched the Criterion collection version, which does cut out the scenes where the possessed nuns take down the crucifix and masturbate with it, and the end scene where Sister Jeanne masturbates with a burned femur bone fragment. I don't think I mind those scenes missing, as it's already pretty obvious the exorcism scene is just a giant public orgy and it doesn't take a genius to know what Jeanne did with that bone.
It's pretty easy to get mired in the sex part of the movie, as that is the most shocking, but I do think it's an interesting look at the all consuming forces of power and religion writ large, as twin flames that feed each other and consume each other. I hesitate to call it a satire, because it seems too small of a word. It's a jester's puppet play, mocking and absurd.
You have power and religion in a small sense, Grandier and Jeanne, who have both used religious power to get what they want and punish when they don't. The movie starts with Grandier in bed with a noble's daughter, who he's been having sex with for a while now. She tells him she's pregnant, and he drops her like a hot rock and tells her to repent. Whoops, shouldn't have gotten pregnant, that's on you. Now she wants nothing more than to help outsiders destroy him.
Jeanne wants Grandier to be the Convent of St. Ursula's confessor, but after finding out he's married another women in secret and turned down Jeanne, she makes up charges that he's been consorting with the devil to punish him.
On a larger level, you have the pope wanting to unite and control all of France, and to control the king through influence. The church, along with baron Laubardemont and the exorcist Barre descend upon the town to whip up a fury, and to debase and control the innocent sisters of the convent. The enema exorcism and later "corrective rape" of Jeanne is the church using religion to control and punish - on a government level, to seize control of the town, and on a personal level over the nuns. They must act as if they have been possessed, or they will die.
At the very end Grandier meets the consequences of him pissing off a bunch of people in high positions, and is stripped down and asked to repent himself. Once a celebrated leader of the town, most of the townspeople have either been whipped into a religious and bloody frenzy or into silence. The city and it's people start out in stark white and black colors, speaking to it's repression and servitude, but at the end the debauchery and bloodlust overwhelm the audience and all of your senses. It all ends in a giant explosion, as the town walls are destroyed, and then silence.
Man I should make an outline for these sort of things, this writeup is all over the place.