What Is Exorcism? How Can A Demon Be Cast Out?
Exorcism is commanding, in the name of Jesus, a demon to come out of an individual, a house, or wherever the demon happens to be. Exorcism is accomplished by the spoken word, in the name of Jesus, through the power of the Holy Spirit, and it is done simply and quickly (see Acts 16:16-18).
The person who is doing the exorcism should be filled with God's Spirit. He should not have any unsurrendered sin in his life, because the demon will take advantage of any weakness. (see Acts 19:13-16). So, this person has to be pure of ulterior motives, sexual impurities, greed, and any other things that might lay him open to some charge by the devil, who is the accuser of the brethren.
Another word of caution: People should not go out looking for demons or make up demons where they do not exist. A believer should be prepared to confront demons when the need arises, but he or she should not go out looking for this kind of encounter.
Excerpt taken from Answers to 200 of Life's Most Probing Questions, Copyright 1984 by Pat Robertson.