This exchange is the film's drama. Sarchie's response is quintessentially American. In his excellent book The Death of Satan: How Americans Have Lost the Sense of Evil, Andrew Delbanco (director of American Studies at Columbia University) argues persuasively that we've lost the conceptual grammar that would help us make sense of evil since we've stopped believing in Satan, devils, and evil.
Delbanco, a self-described secular liberal, argues passionately that our collective anxiety in the aftermath of this loss is mounting into a crisis. Dismissed as an old-time fantasy, Satan has receded into the background—but may have become the more powerful for it.
The idea that Satan has "receded into the background" means combining a police procedural with a supernatural horror film makes a lot of sense. In his excellent book American Cinema / American Culture, John Belton says that one of the cultural anxieties underlying American horror films is that "in the age of reason, reason replaces superstition and irrationality, initiating an interrogation of traditional spiritual and religious beliefs. The horror genre marks a return of that which the age of reason represses or questions—the supernatural, the irrational, and the monstrous."
You get the sense that Derrickson is hyperaware of these cultural tensions and anxieties: the climactic scene is (I don't think it's really a spoiler to say) an exorcism in the middle of an NYPD police interrogation room.
Some of the defining images in the film are shots of Bana, with a disturbed look on his face, shining a flashlight in the direction of some oddity. And one of the defining recurrences is when Sarchie has some supernatural evil flash before his eyes in the midst of investigation. He looks to Butler or Mendoza or anybody for confirmation of what he's seen. The moviegoer is led to investigate along with Sarchie. We think we saw it too, if we can believe our eyes. We're invited to participate—to avail ourselves—in this drama of perception.
All of this sounds serious—and it is—but I don't want to give the wrong expectations: Deliver Us from Evil is also, for all its scares and drama, a buddy cop action comedy, released on the fourth of July with good reason. This will put off some moviegoers who want a film that I've described as "a drama of perception" to have more long-takes and pauses and reflection. I prefer to spend long stretches with Ellison Oswalt in his home office for this reason, but I'm also glad to receive this film for what it is, and what it is—is an intentionally blunt, mainstream genre mixer which goes for subtlety not in its narrative or dialogue but in its more formal filmmaking choices (more on that below).
My one disappointment with the mostly surface-level narrative is that I was unable to become invested in the domestic drama between Sarchie and his wife. I like what Munn is going for in these scenes—graciously available to her husband when he's availed himself to some heavy darkness with the effect of distancing himself from his family.