Real case of Exorcism was it true or its just Mental Disorder

An exorcism is a religious rite for driving Satan or evil spirits out of a possessed person, place, or thing. In ancient times, many cultures had such rites. Today, the Roman Catholic Church still believes in diabolic possession and its priests still practice what is called "real exorcism," a 27-page ritual to drive out evil spirits. The ritual involves the use of holy water, incantations, various prayers, incense, relics, and Christian symbols such as the cross. The Catholic Church has at least ten official exorcists in America today (Cuneo). The Archbishop of Calcutta, Henry Sebastian D'Souza, says he ordered a priest to perform an exorcism on Mother Teresa shortly before she died in 1997 ecause he thought she was being attacked by the devil.

Technically, exorcism is not driving out the Devil or a demon, but it is placing the Devil or demon on oath. And, in some incidences there may be more than one demon possessing a person. "Exorcism" is derived from the Greek preposition ek with the verb horkizo which means "I cause [someone] to swear" and refers to "putting the spirit or demon on oath," or invoking a higher authority to bind the entity in order to control it and command it to act contrary to its own will.

There is no solid evidence that spirits exists and according to one from the angle of skeptics and scientists the people who acts or thinks they are possessed are psychologically ill and require immediate medical help.... though there are many theories why people gets psychologically affected ranges from their family background,environment and their way of living and nutrition they take.......

Although all exorcisms are different in proceeding there are similar stages they follow. Martin describes these stages as :

The Presence: The exorcist and his assistants become aware of an alien feeling or entity. Attempts or actions of the evil spirit appear to be the victim's. The exorcist's first job is to break this Pretense and find out whom the demon really is. Gaining the entity's name is most important.
Breakpoint: The moment when the Devil's Pretense finally collapses. This is usually a moment of complete pandemonium. There evolves a scene of panic and confusion, accompanied by a crescendo of abuse, horrible sights, noises, and odors. The Devil then turns on the victim, speaking of the person in the third person.
The Voice: Also a sign the Breakpoint, the Voice (of the demon) becomes "inordinately disturbing and humanly distressing babble." The demon's voices must be silenced for the exorcism to proceed.
The Clash: As the Voices die out there is both a spiritual and physical pressure. The demon has collided with the "will of the Kingdom." The exorcist is now in direct battle with the demon, urging the entity to reveal more information about itself so it can be controlled. As previously mentioned, there is a connection between the entity and the victim's resident. The entity wants a place to be in, or it must return to Hell. An existence out of Hell is what the Devil or demon is fighting for.
Expulsion: In the supreme triumph of God's will, the demon or spirit leaves in the name of Jesus. All present feel the Presence dissipates, occasionally with receding noises and voices. The victim may remember the ordeal or may not recall anything that has happened.

Most convincing exorcism case of this century is the exorcism of Emily rose there is a a movie based upon her story called "The Exorcism of Emily Rose" the picture shows the real pic of emily rose Emily when she was a teenager

when she was possessed last moments of her life Emilly as a teenager

The detailed story of the Emily rose can be found in this site and also there is a real voice recording of 1952 Emily rose http://www.chasingthefrog.com/reelfaces/emilyrose.php