Requiem works for many reasons--an intelligent script, understated direction, a somewhat verite camera style--but most of all it works because of Sandra Huller. For all of Michaela's exceptionalism, at no point could I doubt this character. As a recovering Catholic myself, I'm sensitive to the role religion, especially Catholicism, plays in people's lives; and Huller, in my opinion, creates the real thing: implicit faith that needs neither to advertise nor to apologize. Michaela's faith isn't about doctrine or rules but the meaning of life--more specifically, about living the meaning of one's own life, including its less attractive implications. Her faith makes her vulnerable to the devil (or, if you prefer, to her imagination that the devil is messing with her), but her faith also endows her growing suffering (and her eventual death, which she clearly foresees; note her reference to "martyrdom" in one of the last scenes) with an abundance of the same meaning that has sustained her life. She is peaceful at the end ("I must walk my path to the end.") That may be hard for a non-religious person to understand, but to someone raised on stories of the great saints, as Michaela was, it makes perfect sense. It is even something to be grateful for.
Requiem pulls off a bit of cinematic legerdemain in making Michaela a relatively open, non-fanatical, non-prudish woman in spite of the depth of her faith. Her real-life original, Anneliese Michel, wasn't much like that. She was a very conservative Catholic deeply opposed to the liberalization then occurring in the Catholic church after the Vatican Council. Her death and the subsequent trial of her parents and the exorcists forced a kind of confrontation, at least in Germany, between Catholic traditionalism, which has an entirely literal belief in spiritual realities and regards demonic possession and exorcism as established facts, and ecclesiastical modernism, which is embarrassed by such medieval notions and therefore preferred to take the position that Michel was "merely" mentally disturbed. (And if she were, did she suffer any the less? Was her faith any less meaningful to her?) Traditionalists regard Michel, her parents, and the exorcists as martyrs to a modernist church disloyal to its Christian past, and Michel's grave is today a pilgrimage site primarily for conservative Catholics. You'd never guess any of this from Requiem's very sympathetic treatment of her story.
