Exorcism is a religious rite intended to drive the devil or other evil spirit out of possessed persons.
The word exorcism comes from the Latin exorcismus and Greek exorkizein meaning “to bind by oath”. The practice is quite ancient and part of the belief system of many cultures and religions. Today, the Roman Catholic Church still believes in diabolic possession and Catholic priests still practice a ritual involving the use of holy water, incantations, prayers, incense, relics, the cross, and other Christian symbols.
Many symptoms of medically-recognized mental illnesses, including hysteria, mania, psychosis, Tourette’s syndrome, epilepsy, schizophrenia or dissociative identity disorder, have been ascribed by believers to possession. There is also a form of monomania called demonomania or demonopathy in which the patient believes that he or she is possessed by one or more demons. Believers aside, demonic possession is not a valid psychiatric or medical diagnosis recognized by either the DSM-IV (American Psychiatric Association) or the ICD-10 (World Health Organization).
Other people, whose brains are more or less healthy, can find themselves sucked into playing a social role by the zeal of believers. Some supposedly possessed persons are actually narcissists or are suffering from low self-esteem and act like a demon possessed person in order to gain attention.
There is no evidence to support that demon-possession is real. It is important to note that the exorcists themselves can cause great harm, and their activities have caused a number of real-world tragedies over the years, including several deaths. The famous 1973 case of Annaliese Michel is an example: her religious Catholic family recruited two priests who performed the exorcism ritual 67 times (!) on the mentally ill woman. At the time of her death, the unfortunate 23 year old weighed a mere 69 pounds.