Summary: The Bible not only teaches that the existence of the devil and demons are real. But, that they were once holy.
The Bible not only teaches that the existence of the devil and demons are real. But, that they were once holy. However, they allowed their leader, Satan to lead them away from God. Their ultimate end will be eternal damnation when God judges the demons and Satan at the Great White Throne of judgment (Revelation 20:10-15).
There are a few things we need to know about demons. They are spirits without bodies (Eph. 6:12), demons as I said before were in fellowship with God at one time (Jude 6). Demons are innumerable (Mark 5:8-9). Demons are organized (Matt. 12:24). Demons have supernatural powers and are knowledgeable about God (Rev. 16:14; Matt. 8:29). Demons are allowed to roam the earth and torment those who do not believe and they can inflict sickness from time to time (Matt. 12:43-45; 9:32-33). Demons can control and possess animals and human beings, as well as cause mental illness (Mark 5:13; 5:2-3,5; Luke 8:2;). Demons know that Jesus is God and tremble before Him (Mark 1:23-24; James 2:19). Demons teach false doctrine and oppose the people of God while trying to destroy God’s Kingdom (1 Tim. 4:1; Eph. 6:12; 1 Peter 5:8). God uses the demons for His purposes and will judge them at the last judgment (Judges 9:23; 2 Peter 2:4), (McDowell 175-177).
The scripture is full of evidence but that evidence is not there for the skeptic because he is not impressed with Scriptural evidence. Scriptural evidence is the most important witness of all. We must remember that everything that God has created has been for Him. The New Testament is full of evidence that demons exist. Their existence is declared in James 2:19 and Revelation 9:20. Their nature is described in Luke 4:33 and 6:18. Their activities are mentioned in 1 Timothy 4:1 and Revelation 16:14. There is evidence of their exorcism from human beings in Luke 9:42. They are organized as told of in Matthew 12:26 and Ephesians 6:12. Luke 8:31 and Revelation 9:11 tells us where they live. In Matthew 25:41 their final end is told to us. Christ himself told his disciples to cast demons out in Matthew 10:1, he cast them out himself in Matthew 15:22,28, rebuked them in Mark 5:8, and in Matthew 12:29 showed his power over them and over Satan in Luke 10:17-18.
There are those out there who need something other than scripture for proof that demons exist. Nature is full of examples of the supernatural world played out in the natural. Illustrations abound that Satan and demons exist. We only need a look at plants and the pests that are continually attacking the farmer. Animals have their natural enemies who kill and feed upon them. The human body is besieged by germs that attack the body with disease and death. These illustrations are not to suggest that there is some connection between the pest and parasites, germs and disease in the natural realm and the demons of the spiritual realm. God is seen in all that is made (Rom. 1:20, my paraphrase).
There are those who may think that Scripture and nature hold no answers as to the existence of demons and Satan. There is proof in human nature. Thomas Davies says, “The belief in evil spirits is universal.” L.T. Townsend concurs in this manner about mankind’s belief in demons, “persistent and widespread . . . as belief in God, in good angels, or in the soul’s immortality” (Unger 38).