The teaching above promoted by a couple of posters on this board is more in line with modern liberal Atheistic Psychology thinking today or established Christadelphianism than biblical Christianity.
The modern psychological model
The modern psychological model views the symptoms described in biblical narratives—such as speaking in multiple voices, exhibiting different personalities, and displaying extreme behavioral changes—as consistent with dissociative identity disorder rather than literal demonic possession.
Christadelphians
Christadelphians do not believe in a supernatural, personal devil, but rather view the "devil" and "Satan" as personifications of sin, evil human nature, and temptation. They interpret these terms to represent the sinful inclinations within individuals, or sometimes a group of people or a political power acting as an opponent. According to this belief, sin originates from within a person's own desires, and the "devil" is not an external being with magical powers, but a metaphorical representation of the struggle against God's will.
The truth!
Do you realize, Satan is not a physical being? He is an angel. He is an invisible spirit. He is a real demonic angelic entity. He is not merely an abstract influence. Even though Satan is an angel of darkness, 2 Corinthians 11:14 tells us that
"Satan himself is transformed into an angel of light. Therefore it is no great thing if his ministers also be transformed as the ministers of righteousness; whose end shall be according to their works."
Angels are spirits (Hebrews 1:14). Demons are fallen angels. They operate in the invisible realm. Their allegiance is to Satan. When the Bible talks about the activity of the devil, it sometimes includes the phrase “and his angels.” They are depicted as a collective whole. They move and fight as a unitary army. You cannot divide Satan from the fate of his angels. For example, Jesus describes them in Matthew 25:41 as
“the devil and his angels.” Revelation 12:7 describes them as
“the dragon … and his angels,” and in Revelation 12:9 as
“that old serpent, called the Devil, and Satan … and his angels.”
Job 1:6-7:
"Now there was a day when the sons of God came to present themselves before the LORD, and Satan came also among them. And the LORD said unto Satan, Whence comest thou? Then Satan answered the LORD, and said, From going to and fro in the earth, and from walking up and down in it."
We can see how the demonic host operates as a collective whole.
Demons are fallen angels
Jud 1:6 “And the angels which kept not their first estate, but left their own habitation, he hath reserved in everlasting chains under darkness unto the judgment of the great day.”
2 Peter 2:4 closely correlates: “God spared not the angels that sinned, but cast them down to hell [Gr. tartaroo], and delivered them into chains of darkness, to be reserved unto judgment.”
This is talking about angels that sinned at the beginning and therefore fell. Adam and Eve were not angels. They are not held in "everlasting chains under darkness unto the judgment of the great day.” God redeemed them. He made an atoning sacrifice for them in the Garden and gave them a righteous covering. Who else is this speaking about than Satan and his demons?
Revelation 12:1-4 shows Satan and his devils being eternally evicted from heaven. Interestingly the demonic angels are depicted as “stars.” It reads:
“And there appeared a great wonder in heaven; a woman clothed with the sun, and the moon under her feet, and upon her head a crown of twelve stars: And she being with child cried, travailing in birth, and pained to be delivered. And there appeared another wonder in heaven; and behold a great red dragon ... And his tail drew the third part of the stars of heaven, and did cast them to the earth.”
In Revelation 12:4, 1/3 of the angels sided with Satan in his rebellion. They sided with him when he fell, and are part of the kingdom of darkness.
Job 38:4-7 tells us, speaking about the beginning of time,
“Where wast thou when I laid the foundations of the earth? declare, if thou hast understanding. Who hath laid the measures thereof, if thou knowest? or who hath stretched the line upon it? Whereupon are the foundations thereof fastened? or who laid the corner stone thereof; When the morning stars sang together, and all the sons of God shouted for joy?”
Revelation 9:1 says:
“I saw a star fall from heaven unto the earth: and to him was given the key of the abyss.”
It seems correct to view the flying star in view here as an elect angel. Remember, the key or authority no longer belongs to Satan. He was defeated. Christ and His angels exercise that now within the invisible realm. We exercise it upon the earth.
It is clear that stars are used by John in Revelation as symbols of angels. A falling star is a common easily-recognized natural symbol that is used in a spiritual way here to describe an elect angel descending from heaven before the end of time to open the pit to release Satan and his demons from their restraint in order to restrict the great commission.
