Exorcism
In Christianity, exorcism is the practice of casting out demons. In Christian practice the person performing the exorcism, known as an exorcist, is often a member of the Christian Church, or an individual thought to be graced with special powers or skills. The exorcist may use prayers and religious material, such as set formulas, gestures, symbols, icons, amulets, etc. The exorcist often invokes God, Jesus and/or several different angels and archangels to intervene with the exorcism. Protestant Christian exorcists most commonly believe the authority given to them by the Father, Son, and Holy Spirit (the Trinity) is the source of their ability to cast out demons.
Gabriele Amorth
Edward Peters, a professor of canon law, finds Amorth's claim to have personally performed 30000 exorcisms over 90 years "astounding". Even accepting Amorth's claim that only 94 of his 30000 exorcisms represented full-blown possession, that would have required roughly one case a month to be thoroughly examined and processed over nine years with hardly a break. Amorth believes that a person may be possessed by more than one demon at once, sometimes numbering in the thousands, which is what accounts for the high number of reputed demons exorcised.