This "fall" consists in the free choice of these created spirits, who radically and irrevocably rejected God and His reign. There is a reflection of that rebellion in the tempter's words to our first parents:"you will be like God" (Gen.3:5). The devil "has sinned from the beginning," he is a liar and the father of lies (1John 3:8).
Jesus came to destroy the works of Satan
Scripture witnesses to the disastrous influence of the one Jesus calls "a murderer from the beginning." who would even try to divert Jesus from the mission received from His Father. "The reason the Son of God appeared was to destroy the works of the devil" (1John3:8). Satan or the devil and the other demons are fallen angels who have freely refused to serve God and His plan. Their choice against God is definitive. They try to associate human beings in their revolt against God.
The power of Satan is not infinite
Satan is only a creature. He is powerful from the fact that he is pure spirit, but he is still a creature. He cannot prevent the building up of God's reign. Satan may act in the world out of hatred for God and his Kingdom in Christ Jesus. His action may cause great injuries of a spiritual nature and, indirectly, even of a physical nature, to each person and to society. The action is permitted by divine providence.
Providence permits diabolical activity.
It is a great mystery that Providence should permit diabolical activity. Devils are permitted to enter the body of human beings and to excercise power over their facuilties, a state known as diabolical possession; or they are permitted to torment a person from without, a state known as diabolical obsession. Diabolical possession and obsession are permitted by God to show forth His glory, to punish sin, to bring sinners to repentance, or to give occasion for the exercise of virtue. When the devil uses the body of the possessed person to say or to do evil things, the person is not guilty of sin, provided he does not fully consent. Exorcism is the act of driving out or warding off evil spirits from persons, places, or things possessed or infested by them. The Church received from Christ the power of exorcism. Only with the permission of a bishop is a priest allowed to use his power of exorcising evil spirits.
God permitted such painful upheavels as the angels' fall and man's sin only as occasions and means for displaying the whole measure of love he wanted to give to the world.
"We know that in everything God works for good with those who love Him." (Rom.8:28).
