When the movie adaptation of William Peter Blatty’s The Exorcist opened the day after Christmas 1973, few who saw the picture could have imagined the film’s staying power. Over budget with no star names, the studio did not have high expectations for its returns and were shocked by its wild success. Even in the 1970s, demonic possession was increasingly rationalized away as medical and psychological knowledge expanded, reducing it to an exaggerated explanation of the unknown. Fifty years later, there is even less reason to believe the events depicted in the story and more reason to write them off as superstitious nonsense only useful for cheap scares. Given the strong social preference of rationality to faith as well as the sharp increase in irreligious or atheistic views in recent years, how does a movie so clearly about the battle between good and evil still maintain its power, even over those who claim little to no belief in a higher authority?

In nearly every interview he gave in the last years of his life, director William Friedkin referred to The Exorcist as a movie about “the mystery of faith,” a quote taken directly from the film, during a scene in which Father Karras gives the Eucharist. Friedkin repeatedly claimed he never thought of The Exorcist as a horror movie and felt that those who went to see it without emphasizing its spiritual component had an incomplete understanding. Regardless of one’s religious views, it is worth noting that upon multiple viewings, the scenes depicting demonic possession, despite maintaining their ability to unnerve and frighten, fade into the background. It is the relationship between the world of priests and the world of laymen, personified in scenes between Chris (Ellen Burstyn), the actress mother willing to give doctors the benefit of the doubt until they come up empty-handed, and Father Karras (Jason Miller), the chain-smoking alcoholic university psychiatrist who fears he is losing his faith amidst growing guilt over the death of his mother, that is most compelling. That particular relationship – between a mother doing everything she can to help her child and a righteous man questioning his values – is relatable, for it involves two people striving for good and failing, and in need of support.

During the climactic scenes involving the arrival of famed priest Father Merrin (Max von Sydow), where the two clergymen unite to fight the evil spirit inhabiting young Regan MacNeil (Linda Blair), Friedkin’s note about “the mystery of faith” is made clear. This is the moment of the movie given the most care, the most attention and the most importance, without any distractions or gimmicks. It is apparent that tremendous intensity and focus are needed to combat a force that, seemingly out of nowhere, has arisen and threatens the life of a twelve-year-old girl and, potentially, others. Without pumping up the music or using quick cuts or editing tricks, Friedkin holds our attention throughout the sequence as the two priests begin the ritual, not to exorcise the demon themselves but to ask for Jesus Christ to intervene on their behalf. Unlike its inferior descendants, The Exorcist refuses to depict this battle as anything other than a fight between good and evil. Each side is clearly demarcated, but the battle is accurate in the sense that good must work a lot harder to defeat what has fairly easily become possessed by evil. At one point, the priests must rest because it isn’t a matter of simply demanding God’s assistance; they must prove themselves worthy of standing up to this corporeal presence that, because it has overtaken a human, needs human intercessors.

Additionally, the demon is depicted as seriously as the priests and their internal conflicts. Memorably voiced by radio actor Mercedes McCambridge, Pazuzu (a Mesopotamian entity said to represent the southwestern wind) exhibits anti-social behavior primarily through taunting and sexual perversity. These actions have even more power than usual because of the use of young Regan as a vessel, but nothing is played for laughs or irony. When Karras first converses with Pazuzu to test its legitimacy, the demon taunts him but also becomes defensive when asked to display its power. It also continuously lies, as Merrin warns, and to be seduced into its web of lies is to fall victim to its trap, making one compromised. But to be seduced does not mean that one is incapable of standing up to evil. Through the arc of Karras, we see redemption is within reach, primarily through self-sacrifice, which is personified archetypally in the life of Christ Himself.

In the subsequent decades, many filmmakers, critics and fans have discussed The Exorcist ad nauseum, frequently describing it as “the scariest movie of all time,” or alluding to its ability to continuously impact younger generations who otherwise are inured to graphic imagery and mature content at a much earlier age. What is so striking is that many commentators and fans of the movie would have little to no problem describing themselves as non-religious in some capacity. Yet, why does a religiously minded movie still have such impact? After all, if one feels confident that something does not exist, how can a fictional depiction of said thing have any type of effect outside of its artistic ambitions and achievement? Is it possible that The Exorcist works, and can only work, because of the seriousness with which the film approaches its otherwise lurid and fantastical subject matter? Friedkin wisely keeps the movie out of such discussions, but the debate over the legitimacy of including ancient religious rites that even most Catholics have never witnessed as subject for horror thrills seems to have been settled. Countless sequels, remakes and other forms of cinematic rip-offs of The Exorcist have been made and continue to be made up to the present day (see The Exorcist: Believer). The question for all of these movies is how serious they take the concept of evil personified in the form of demonic possession. Is it merely a tool to elicit cheap thrills and a good time, or is there a larger purpose in showing disturbing images that are meant to frighten and unsettle? In this age of irony where nothing seems safe from mockery and contempt, Friedkin’s belief, exemplified in The Exorcist, that good and evil runs through everyone is in danger of becoming mere fodder for a chaotic mill.