AceShowbiz - In many cases of haunting and possession, exorcism is often performed to cast out the demon. In "The Exorcist" (1973), the act is performed on a possessed child by priests, showing the religious element which is highly influenced by the tradition in Catholic Church. In Catholic Christianity, a formal exorcism which is called a Major Exorcism has to be carried out by an ordained priest based on strict guidelines. Jesus Himself set the example of exorcism as, based on the New Testament, He exorcised a demon or demons out of a man and saved a possessed daughter of a woman in Canaan.
The practice of exorcism is also found in other religions, though it is carried out in different ways. In other cases like the ones depicted in "The Conjuring" and "Poltergeist" (1982), the characters seek the help of spiritual practitioners to evict ghosts from haunted houses. Though they sound odd, paranormal investigators and spiritual mediums are real jobs. Ed and Lorraine Warren, who are portrayed by Patrick Wilson and Vera Farmiga respectively in "The Conjuring", are the real examples. That's why the events in the first film as well as the sequel "The Conjuring 2" are claimed to be based on true stories on the cases handled by the ghost-hunting duo.