From a Greek word signifying to conjure, to use the name of God or certain magical ceremonies with design to expel devils from places or bodies which they possess. The apostles were enabled to cast out evil spirits in Christ's name, Mt 10:1; Mr 16:17; Lu 10:17; and designing men, both before and after the Savior's death, pretended to exercise the same power, Mt 12:27; Mr 9:38; Lu 9:49-50; Ac 19:13-17. Exorcists were thought to have gained this power by secret studies respecting the nature of demons, and the powers of certain herbs, drugs, and stones, and were accustomed to use various forms of adjuration and incantation in their unlawful art; but the whole was delusion and imposture, and strictly forbidden. See DIVINATION.
The incident recorded in Ac 19:13-16, raises the question as to what was an 'exorcist'? The disciples of the Lord who were able to cast out demons were never so called. Were these vagabond or wandering Jews able to cast out demons irrespective of the name of the Lord Jesus? or did they only pretend to do so? Mt 12:27 is often quoted to show that the Lord admitted that such persons were able to cast out demons. Is it not more probable that the Lord was in that passage alluding to His disciples? The Lord was a mysterious person whom they could not comprehend; and He was charged with casting out demons by the prince of demons; but the Lord said, By whom do your children (the origin of whom you do know) cast them out? On the other hand, the Lord describes some of the lost as pleading that they had cast out demons in His name, Mt 7:22; but these also speak of having prophesied in His name; so that they would be persons who had made a profession, as Judas who was sent out with the other apostles.
On one occasion the disciples met with a man who was casting out demons in the name of the Lord, whom they forbade because he followed not with them; but the Lord said that no one who did a miracle in His name could lightly speak evil of Him. Mr 9:38; Lu 9:49. On the whole it seems plain from scripture that the casting out demons could only be by the power of God. As explained by the Lord, Satan would not destroy his own kingdom. What power the exorcists really had we know not, but in the case under consideration God did not allow them to use the name of the Lord Jesus, and the demon overpowered and wounded them.