Exorcism
In Christianity, exorcism is the practice of casting out demons. In Christian practice the person performing the exorcism, known as an exorcist, is often a member of the Christian Church, or an individual thought to be graced with special powers or skills. The exorcist may use prayers and religious material, such as set formulas, gestures, symbols, icons, amulets, etc. The exorcist often invokes God, Jesus and/or several different angels and archangels to intervene with the exorcism. Protestant Christian exorcists most commonly believe the authority given to them by the Father, Son, and Holy Spirit (the Trinity) is the source of their ability to cast out demons.
The Last Exorcism
Filmmakers Iris and Daniel follow Cotton Marcus, a reverend living in Baton Rouge, Louisiana, who seeks to delegitimize exorcisms. Marcus, who lost his faith after the birth of his ill son, is accustomed to performing fake exorcisms on "possessed" individuals. He accepts an exorcism request sent by farmer Louis Sweetzer, who claims his livestock are being slaughtered by his daughter Nell; Louis suspects that Nell is possessed by Satan.