There are a few different theories about where demons came from. Here they are:
(1) Dead people – Some early Christians thought this was the case and it has remained a popular theory even to this day. The problem with this theory is that Lk 16:23 says that evil people are in hell after they die.
(2) Race of People before Adam – This theory is based on the “gap theory” of Genesis. The idea is that there is a gap between Genesis 1:1 and 1:2 and that there was a race of people who rebelled against God which caused them to fall into this demonic state. The problem with this view is that there is no evidence in Scripture that these people ever existed. Also Romans 5:12 says that sin entered the world with Adam. If these guys existed and fell sin had to existed before Adam.
(3) Offspring of Angels and women. Genesis 6:2 says that the “sons of God” had intercourse with the “daughters of men” and created a race of demons called the Nephilim. Scripturally though, there is no indication that the Nephilim were not people or that the “sons of God” were not also people. The verses say they took them as their wives which actually indicates that they were human.
(4) Fallen but unconfined angels. This is the most likely view. When Lucifer rebelled against God, he fell from his place of honor and a bunch of angels went with him. Mt 25:41 actually refers to demons as “angels” so this seems like a probable view. Scripture says there are 2 groups of fallen angels: (1) 2 Pet 2:4 talks about a group who are confined in hell permanently. (2) Lk 8:31; Rev 9:2-11 refers to a group who are imprisoned in a pit. They were “too depraved to and harmful to be allowed to roam upon the earth” but they will be released during the Tribulation to afflict people who don’t have the seal of God on their foreheads.
What are demons like?
1. They are spirit beings. (Mt 8:16; Lk 10:17, 20) They do not have bodies of flesh.
2. They are not omnipresent. They can only be in one place at a time. (Mt 8:28-34)
3. They are intelligent, but not omniscient. (Mk 1:24; Mt. 8:29; 1 Tim 4:1)
4. They are powerful, but not omnipotent. (Mk 5:3-4; 9:22; Mt 9:32; 15:22; Jn 10:21)
What do they do?
1. Inflict disease. (Lk 13:11, 16; Job 1:12; 2:6)
2. Influence the mind. (Gen 3:1-5; 2 Cor 4:4; 11:3)
3. Deceive people. (1 Thes 3:5; Eph 2:2; Mt 13:19)
4. Deceive nations. (Rev 16:14)
5. Possess people. (Mt 4:24; 8:16, 28, 33; 12:22; 15:22; Mk 1:32; 5:3-4, 15, 16, 18; Lk 8:36; Jn 10:21)
Christ has defeated demons! (Col 2:15)
They will be thrown into the lake of fire! (Mt 25:41; Rev 12:9; 19:19-21)
How does this change my life? I’m able to recognize the work of demons more readily and can in turn pray against them. This information also will help me in answering the questions of the youth I work with. Spiritual issues like this are very interesting to students and in answering their questions, I have opportunities to share the good news of the demon’s defeat. Also with good answers to their questions, I can gain the students respect and trust for future conversations.
(Info from “The Moody Handbook of Theology” by Paul Enns, pg 295-298)