Despite its title and pile-up of such spectacular images, Exorcism is actually less about the exorcism than about how to interpret what happens to Emily. While the movie plainly shows her possessed, doubts arise in legal, social, and "scientific" explanations (is she anorexic, psychotic, in need of medication?). Cutting among the courtroom scenes (the wondrous Shohreh Aghdashloo makes a brief appearance as a scientist who defends the exorcism), Erin's own lonely encounters with demons (or sinister shadows and noises at her home, at least), and Emily's rapidly escalating symptoms (including speaking in multiple voices, eating bugs, starving, and abusing herself and others physically), the film makes Father Moore's case, that even if you don't believe (like Erin), demons exist. And they'll plague you just to make that point.
Demonstrating their existence appears to be Father Moore's focus as well. He insists, against Erin's advice, that he testify. "What matters most is that I tell Emily's story," he says, having heard her version of a vision whereby she learns her suffering and example are God's will. While the Archdiocese and scientific and legal communities are trying to explain the event, Emily's "story" is that the explanation is a function of faith. She's chosen. The most compelling question arising from Scott (Hellraiser: Inferno) Derrickson's revisitation of the story has to do with audience and timing. Why now? What's at stake for current audiences, not only in Emily's ordeal, but in the arguments around it? And what sort of refitting makes it suitable for a PG-13 rating, aside from the omission of Linda Blair's green-pea soup vomit and Mercedes McCambridge's obscenities in the William Friedkin version?