Exorcism
In Catholic Christianity, exorcisms are performed in the name of Jesus Christ. A distinction is made between a formal exorcism, which can only be conducted by a priest during a baptism or with the permission of a bishop, and "prayers of deliverance" which can be said by anyone.
The Catholic rite for a formal exorcism, called a "Major Exorcism", is given in Section 11 of the Rituale Romanum. The Ritual lists guidelines for conducting an exorcism, and for determining when a formal exorcism is required. Priests are instructed to carefully determine that the nature of the affliction is not actually a psychological or physical illness before proceeding.
The Last Exorcism
During the exorcism, "Abalam" agrees to release Nell only if Marcus can remain silent for ten seconds. Each second, Nell breaks one of her fingers. After three, Marcus yells for Abalam to stop; Abalam asks Marcus if he wants a "blowing job". Marcus challenges that a demon would know the actual name of the sex act and concludes that Nell is not possessed, but a disturbed and ashamed girl. Nell anguishes over losing her virginity to a boy named Logan, which Louis again rejects. Marcus and the crew meet Logan, who explains that he is homosexual and the only contact he had with Nell was a brief conversation at Manley's house six months ago; the crew realizes Manley was lying about having not seen Nell. They return to the Sweetzer farmhouse, which they find empty and covered with numerous occult and countercultural symbols on its walls.