The film’s strengths come from William Peter Blatty’s writing and direction, as well as the casting choices, particularly Brad Dourif and George C. Scott; however, problems arise due to studio interference – specifically a rushed exorcism scene added at the last minute with a replacement priest. It's telling that Burton’s Father Lamont from *Exorcist II: The Heretic* is more memorable than Nicol Williamson’s Father Morning. Unlike *The Heretic*, this third installment visually and tonally feels like it belongs in the same universe as *The Exorcist*; it understands the language and the music, with the exception of a strange dream sequence featuring Fabio and Patrick Ewing appearing as angels. There are unsettling images that linger afterward (the crucifix opening its eyes, an elderly woman crawling on the ceiling, Scott’s daughter narrowly escaping decapitation). The film also possesses a sense of humor I'd describe as Shakespearean; Father Joseph Dyer (Ed Flanders), whose lines include a reference to Mel Brooks’ *Spaceballs*, is comparable to the gravedigger in *Hamlet* or the porter in *Macbeth*. My main issue with this movie, similar to what I found problematic about *The Heretic* – though to a lesser extent –, concerns the explanation of how Patient X, also known as Father Damien Karras (Jason Miller), ended up in a hospital psychiatric ward for fifteen years. It’s fortunate that Blatty chose to have X portrayed by both Miller and Dourif—and especially Dourif—because James ‘The Gemini Killer’ Venamun, played by Dourif, delivers an extended speech that ties up loose ends, demonstrating that sometimes you can indeed improve something seemingly worthless; it still doesn't quite make sense even when supernatural elements are considered (the body of a well-regarded local priest emerging from his "cheap little coffin" and disappearing without anyone noticing? Come on), but the performance itself is captivating. Dourif gives a genuinely frightening, chilling story-telling performance—at one point he pauses to question “is this true?” as if struggling to believe it himself. I'm not suggesting Miller couldn’t have handled it, but looking back, I can’t imagine anyone else being able to; I simply know Dourif did because I witnessed him do so in a scene-stealing performance that significantly increased my already high regard for his talent and skill.

Source on TMDB