Exorcists are among the most widely known and misunderstood priests in the Catholic Church. Movies are made about them that make them appear to be "demon hunters," searching out evil spirits that are tormenting individuals.
In reality, exorcists are not well known within the Catholic Church, and lead rather hidden lives.
Generally speaking, an exorcist is a priest in the Catholic Church who is given the task of investigating cases of possible demonic influence.
This priest is appointed by the local bishop, but not all dioceses have an official exorcist "on staff." According to some reports, the number of specially appointed exorcists is only around 50 priests for the entire United States.
Many of these priests are common parish priests, who have their own pastoral duties, but who also spend some time responding to calls of possible demonic possession.
Demonic possession is a tricky issue, as mental illness could be the primary cause of a person's actions, rather than an evil spirit.
Cases of full demonic possession are rare, but exorcists also respond to calls of demonic oppression and locations that appear "haunted."
An exorcist will often meet with individuals, pray official prayers of exorcism formulated by the Church, and invoke God's power to drive out a demonic influence.
The exorcist is technically not the one who drives out a demon. He acts as a instrument of God, interceding for someone, asking God to show forth his power.
Above all, priests who become exorcists are holy men who do not seek out this ministry for power or self-gain, but are called by God for this task. It takes many years of careful study before a priest is properly prepared for such an endeavor, and the ministry is not taken lightly.