For He had said to him, "Come out of the man, you unclean spirit!" Now there on the hillside a great herd of swine was feeding; So He gave them permission. And the unclean spirits came out and entered the swine; and the herd, numbering about two thousand, rushed down the steep bank into the sea, and were drowned in the sea (Mark 5:8,11,13).
These demons entered pigs after previously inhabiting humans.
More Than One
In some instances, more than one demon entered into the same victim. As with the case of the Gadarene demoniacs, there were a number of demons inhabiting those men.
We also have the testimony about Mary Magdalene.
Mary, called Magdalene, from whom seven demons had gone out (Luke 8:2).
2. Inflict Mental Disease
Demons have the ability to inflict mental disease. One of the Gadarene demoniacs was described as follows.
for he had often been restrained with shackles and chains, but the chains he tore apart, and the shackles he broke in pieces; and no one had the strength to subdue him. Night and day among the tombs and on the mountains he was always howling and bruising himself with stones (Mark 5:4,5).
3. Inflict Physical Infirmities
They are capable of imposing physical disease. We find demons inflicting the following illnesses upon people.
Demons have the ability to keep someone from using their powers of speech.
And when the demon had been cast out, the one who had been mute spoke; and the crowds were amazed and said, "Never has anything like this been seen in Israel" (Matthew 9:33).
According to Jesus, a woman had a physical deformity that was caused by a spirit.
And just then there appeared a woman with a spirit that had crippled her for eighteen years. She was bent over and was quite unable to stand up straight (Luke 13:11).
He then emphasized this woman was suffering because of Satan.
And ought not this woman, a daughter of Abraham whom Satan bound for eighteen long years, be set free from this on the sabbath day? (Luke 13:16).
Blindness can also be a side affect of demonic activity.
Then they brought to Him a demoniac who was blind and mute; and He cured him, so that the one who had been mute could speak and see (Matthew 12:22).
Demons can affect both the physical and the spiritual nature of a person at the same time.
There are many possible causes for physical disease. Most times it is as simple as being exposed to some virus or bacteria, or the simple breaking down of the human body.
Judgment For Sin
Sometimes sickness is a judgment of God for sin.
For this reason many of you are weak and ill, and some have died (1 Corinthians 11:30).
Ultimately, we do not know why someone is sick. Therefore we should not assume that it is the judgment of God, or the activity of demons.
4. Cause Erratic Behavior
We find the influence of demons causing people to behave strangely.
and said, "Lord, have mercy on my son, for he is an epileptic and he suffers terribly; he often falls into the fire and often into the water. And I brought him to Your disciples, but they could not cure him." Jesus answered, "You faithless and perverse generation, how much longer must I be with you? How much longer must I put up with you? Bring him here to Me." And Jesus rebuked the demon, and it came out of him, and the boy was cured instantly (Matthew 17:15-18).
5. Harm Unbelievers
Scripture gives us an example of unbelievers being harmed by demons.
Then some itinerant Jewish exorcists tried to use the name of the Lord Jesus over those who had evil spirits, saying, "I adjure you by the Jesus whom Paul proclaims." Seven sons of a Jewish high priest named Sceva were doing this. But the evil spirit said to them in reply, "Jesus I know, and Paul I know; but who are you?" Then the man with the evil spirit leaped on them, mastered them all, and so overpowered them that they fled out of the house naked and wounded (Acts 19:13-16).
6. Deceive Nations
Entire nations can be deceived by the work of demons.
These are demonic spirits, performing signs, who go abroad to the kings of the whole world, to assemble them for battle on the great day of God the Almighty (Revelation 16:14).
Their work is not confined to individuals, but can include entire nations.
Exercised Within Limits
It must be emphasized that the power of demons is limited. They cannot do anything they wish. Their ability to do evil is kept under control by the Lord.
The influence of demons can be seen by a number of things which they do. They can enter into people and animals, inflict mental and physical infirmities, cause people to behave erratically, and even deceive entire nations. Though their power is far-reaching, it can only be exercised within limits.