The reality and personality of this host of evil spirits is taught in Scripture; and a careful study of the numerous passages in which they are mentioned will reveal how God has provided complete instruction in His Word concerning this theme on which so much of the believer's welfare depends.
These spirits are usually referred to in both the Authorized and Revised Versions of the New Testament as "devils," but the word might better have been translated "demons."
In considering the service these beings render to Satan, it is important to distinguish between demon possession or control, and demon influence. In the one case the body is entered and a dominating control is gained: while in the other case a warfare from without is carried on by suggestion, temptation, and influence.
Investigation of the Scriptures in regard to demon possession reveals:
First: That this host is made up of bodiless spirits only. The following Scripture verifies this statement: "When the unclean spirit is gone out of a man, he walketh through dry places, seeking rest, and findeth none. Then he saith, I will return into my house from whence I came out; and when he is come, he findeth it empty, swept, and garnished. Then goeth he, and tak'eth with himself seven other spirits more wicked than himself, and they enter in and dwell there: and the last state of that man is worse than the first" (Matt. 12:43-45). "And all the devils besought him, saying, Send us into the swine, that we may enter into them" (Mark 5:12).
Second: They are, however, not only seeking to enter the bodies of either mortals or beasts (for their power seems to be in some measure dependent upon such embodiment); but they are constantly seen to be thus embodied, according to the New Testament. A few of these passages are given here: "When the even was come, they brought unto him many that were possessed with devils: and he cast out the spirits with his word, and healed all that were sick" (Matt. 8:16). "As they went out, behold, they brought to him a dumb man possessed with a devil. And when the devil was cast out, the dumb spake" (Matt. 9:32, 33). "And the people with one accord gave heed unto those things which Philip spake, hearing and seeing the miracles which he did. For unclean spirits, crying with loud voice, came out of many that were possessed with them: and many taken with palsies, and that were lame, were healed" (Acts 8:6,7). "And it came to pass, as we went to prayer, a certain damsel possessed with a spirit of divination met us, which brought her masters much gain by soothsaying" (Acts 16:16). "And they came over unto the other side of the sea, into the country of the Gadarenes. And when he was come out of the ship, immediately there met him out of the tombs, a man with an unclean spirit, who had his dwelling among the tombs; and no man could bind him, no, not with chains: because that he had been often bound with fetters and chains, and the chains had been plucked asunder by him, and the fetters broken in pieces: neither could any man tame him. And always, night and day, he was in the mountains, and in the tombs, crying, and cutting himself with stones. But when he saw Jesus afar off, he ran and worshipped him, and cried with a loud voice, and said, What have I to do with thee, Jesus, thou Son of the most high God? I adjure thee by God, that thou torment me not. For he said unto him, Come out of the man, thou unclean spirit. And he asked him, What is thy name? And he answered, saying, My name is Legion: for we are many. And he besought him much that he would not send them away out of the country. Now there was nigh unto the mountains a great herd of swine feeding. And all the devils besought him, saying, send us into the swine, that we may enter into them. And forthwith Jesus gave them leave. And the unclean spirits went out, and entered into the swine: and the herd ran violently down a steep place into the sea, (they were about two thousand;) and were choked in the sea" (Mark 5:1-13).
Third: They are wicked, unclean, and vicious. Many passages might be quoted in proof of this statement: "And when he was come to the other side of the country of the Gergesenes, there met him two possessed with devils, coming out of the tombs, exceeding fierce, so that no man might pass by that way" (Matt. 8:28). "And when he had called unto him his twelve disciples, he gave them power against unclean spirits, to cast them out, and to heal all manner of sickness and all manner of disease" (Matt. 10:1). "There met him out of the tombs a man with an unclean spirit, who had his dwelling among the tombs; and no man could bind him, no, not with chains: because that he had been often bound with fetters and chains, and the chains had been plucked asunder by him, and the fetters broken in pieces: neither could any man tame him. And always, night and day, he was in the mountains, and in the tombs, crying, and cutting himself with stones" (Mark 5:2-5). "And they brought him unto him: and when he saw him, straightway the spirit tare him; and he fell on the ground, and wallowed foaming" (Mark 9:20).
It might be added that there seem to be degrees of wickedness represented by these spirits: for it is stated in Matt. 12:43-45 that the demon, returning to his house, "taketh with himself seven other spirits more wicked than himself."
The question is often raised whether demon possession obtains at the present time. Although the authentic records of such control are almost wholly limited to the three years of the public ministry of Jesus, it is incredible that demon possession did not exist before that time, or has not existed since. In this connection it should be remembered that these beings are not only intelligent themselves, but that they are directly governed and ordered by Satan, whose wisdom and cunning are so clearly set forth in the Scriptures. It is reasonable to conclude that they, like their monarch, are adapting the manner of their activity to the enlightenment of the age and locality. It is evident that they are not now less inclined than before to enter and dominate a body. Demon possession in the present time is probably often unsuspected because of the unrecognized fact that demons are capable of inspiring a moral and exemplary life, as well as of appearing as the dominating spirit of a spiritist medium, or through the grosser manifestations that are recorded by missionaries from heathen lands. These demons, too, like their king, will appear as "angels of light" as well as "roaring lions," when by the former impersonation they can more perfectly further the stupendous undertakings of Satan in his warfare against the work of God.
Demon influence, like the activity of Satan, is prompted by two motives: both to hinder the purpose of God for humanity, and to extend the authority of Satan. They, therefore, at the command of their king, willingly co-operate in all his God-dishonoring undertakings. Their influence is exercised both to mislead the unsaved and to wage an unceasing warfare against the believer (Eph. 6:12).