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.
Exorcism in the Catholic Church
In the process of an exorcism the person possessed may be restrained so that they do not harm themselves or any person present. The exorcist then prays and commands for the demons to retreat. The Catholic Priest recites certain prayers the Our Father, Hail Mary, and the Athanasian Creed. Exorcists follow procedures listed in the ritual of the exorcism revised by the Vatican in 1999. Seasoned exorcists use the Rituale Romanum as a starting point, not always following the prescribed formula exactly. "The Gale Encyclopedia of the Unusual and Unexplained" describes that an exorcism was a confrontation and not simply a prayer and once it has begun it has to finish no matter how long it takes. If the exorcist stops the rite, then the demon will pursue him which is why the process being finished is so essential. After the exorcism has been finished the person possessed feels a “kind of release of guilt and feels reborn and freed of sin.” Not all exorcisms are successful the first time; it could take days, weeks, or months of constant prayer and exorcisms.