Exorcism refers to a religious ritual in which an officially delegated priest casts out the devil from a person, object, or place in the name of the Triune God.
The delegated priest acts in the name of Jesus Christ. This designation from Christ can be found in Luke’s Gospel 9:1, “And He (Jesus) called the twelve (apostles) together and gave them power and authority over all demons and to cure diseases, and He sent them out to preach the Kingdom of God and to heal.”
The ability to perform public exorcisms is related to the sacrament of Holy Orders. By this sacrament, any priest or bishop has the sacramental power to perform exorcisms; however, the jurisdiction to do so is limited to an appointment by the bishop of the diocese. When the bishop goes about appointing an exorcist, he looks for qualities of holiness and strength. Before 1972 there was a formal Minor Order of Exorcists. As part of the reforms of the Second Vatican Council and suppressions of the Minor Orders, the 1983 Code of Canon Law, Canon 1172, states the current understanding of an exorcist: “No one can legitimately perform exorcisms over the possessed unless he has obtained special and express permission from the local ordinary.”
Formal public exorcisms are rare. Diabolical possession (where the devil inhabits a person’s body) or diabolical obsession (where the devil attacks a person’s body from the outside by flying objects around the room or trying to injure the body) requires this special and ancient ritual of the Catholic Church.
The movie The Exorcist accurately depicts the exorcism ritual. The Hollywood effects, however, of throwing up pea soup, floating in the air, etc., while real and possible, are rarer. Speaking in foreign languages the person never knew, or mysterious and bizarre voices coming from the person, occasionally occur. The process of exorcism only takes place after the local bishop has concluded an official inquiry. All medical and psychological explanations and treatments must be attempted first. Only after the doctors and scientists cannot remedy the situation through modern medicine and psychiatry is the exorcist allowed to get involved. This prevents hysteria and superstition. The failure of medicine and science to solve the mystery can be a sign of the supernatural.
The Psalms and passages from the Bible, especially the Gospels where Jesus expelled demons from the possessed, are recited by the priest performing the exorcism and the other priest or deacon who accompanies him. Holy water is sprinkled frequently on the person, rosaries are prayed, the Bible is read aloud again, and the formal prayers of exorcism are said. Usually, this is done completely in Latin.
This whole process can take several hours, if not days, and, in some cases, weeks. Doctors and nurses are kept nearby should the possessed person need immediate medical treatment. The possessed rarely become possessed because of something they have said or done. Just like physical injury can indiscriminately hit the good and bad alike, one should never think or conclude that only sinful, evil, or immoral people get possessed. The only reason why these things happen is so that the power and majesty of God can be manifested when the possessed are delivered from their bondage, and we see clearly that good triumphs and is victorious over evil.
In addition to the formal exorcism that is reserved only to a priest or bishop, there are minor ones in which all the faithful can participate. Usually, these types of exorcisms involve holy water. When objects are blessed they are often reserved for good and all evil is asked to be removed. Taking of holy water, making the sign of the cross, and sprinkling of Holy Water on objects or in the home can all be done by lay people. The water is blessed by a priest, but then can be used by laity.
The prayer to Saint Michael the Archangel is considered to be a prayer of exorcism. This prayer used to be said by Catholics at the end of Mass:
Saint Michael the Archangel, defend us in battle, be our protection against the wickedness and snares of the devil; may God rebuke him, we humbly pray and do thou, O Prince of the heavenly host, by the power of God, thrust into hell Satan and all evil spirits who wander through the world for the ruin of souls Amen.
Finally, the wearing of the medal in honor of Saint Benedict is also seen as a devotion and prayer of exorcism.