Exorcism
In Catholic practice the person performing the exorcism, known as an exorcist, is an ordained priest. The exorcist recites prayers according to the rubrics of the rite, and may make use of religious materials such as icons and sacramentals. The exorcist invokes God—specifically the Name of Jesus—as well as members of the Church Triumphant and the Archangel Michael to intervene with the exorcism. According to Catholic understanding, several weekly exorcisms over many years are sometimes required to expel a deeply entrenched demon.
The Exorcist (novel)
After several unsuccessful psychiatric and medical treatments, Regan's mother, an atheist, turns to a local Jesuit priest for help as Regan's personality becomes increasingly disturbed. Father Damien Karras, who is currently going through a crisis of faith coupled with the loss of his mother, agrees to see Regan as a psychiatrist, but initially resists the notion that it is an actual demonic possession. After a few meetings with the child, now completely inhabited by a diabolical personality, he turns to the local bishop for permission to perform an exorcism on the child.