The Bible explains that when God created the heavens and the earth everything was very good (Genesis 1:31) so Satan and his demons as we know them had not come into being yet.
What we know about the fall of Satan and his evil angels mainly comes from two Old Testament prophets and close associates of Jesus. Satan is described by various names in the Bible including Lucifer (Isaiah 14:12), Beelzebub (Matthew 12:24-27), the serpent (Genesis 3), and the dragon (Revelation 12). Demons are referred to as serpents and scorpions. (Luke 10:19)
The Prophet Ezekiel said concerning the fall of the devil that even though he was originally perfect in his ways (Ezek 28:15) and walked in the Garden of Eden (Ezek 28:13), the devil became puffed up by his own beauty (Ezek 28:17). He became filled with violence and sin and so he was cast out of heaven. (Ezek 28:16)
Similarly another prophet, Isaiah, described how Lucifer tried to exalt himself with a throne above the stars of God, so he was brought down to hell. (Isaiah 14:12-33)
A younger brother of Jesus, Jude, wrote that the angels did not keep their proper place so they are kept in chains in hell until the Day of Judgment. (Jude 6) And the great Apostle Peter wrote almost identically in his Second Epistle that the angels were cast from heaven and held in hell for punishment. (2 Peter 2:4)
The battle to force Satan out of heaven is illuminated by the Apostle John when he writes that war broke out in heaven and Archangel Michael and his angels fought with the dragon and his followers and cast them down to the earth. (Revelation 12:7-9)
Much of our modern understanding of the activities of Satan since his fall comes from Jesus and the New Testament. Jesus declared He watched Satan fall like lightening from heaven. (Luke 10:18) The New Testament constantly warned that Satan and his demons strive to undermine our relationship with God. (John 8:44; 2 Corinthians 4:4; Galatians 4:8; 1 Peter 5:8-9). Most Evangelical Christians are familiar with the declaration of the Apostle Paul that we do not wrestle with flesh and blood but with powers of darkness and wickedness in the spiritual realm. (Ephesians 6:12)
However, contrary to movie hype, they have limited powers. Satan needs to ask permission to test us. (Job 1:12; Job 2:6; Luke 22:31-32). We will never be tested beyond our ability to withstand. (1 Corinthians 10:13) There is no evidence in Scripture that demons can read minds, but demons can listen in on conversations. Unlike the nature of God, which is everywhere, Satan can only be in one place at a time, and so he relies on his hosts of demons to move about for him.
Satan and demons are not farsighted and often are stupid and foolish. (Luke 22:33; John 13:27; 1 Corinthians 3:19) James, another brother of Jesus, wrote that when we resist the devil he will flee. (James 4:7)
Another way Hollywood gets it wrong is in depicting Satan in some ways as almost likeable. There is nothing remotely attractive or endearing about Satan. He is incarnate evil, sorrow, pain, and suffering who can only lead to ruin and death.
Also Satan and demons are far less powerful or important than humans. God created women and men in God’s own image (Genesis 1:27). That does not refer to physical attributes such as breasts, or beards, or having nice brains, but rather, means that we are the only entities in all of creation with the ability to love one another and appreciate that love conquers all. (1 Corinthians 13) Not even angels in heaven are created in God’s image. I suspect that the reason that the angel Lucifer turned into evil Satan was out of jealousy over the intimate and loving relationship between humans and God.
So even though Satan and demons are weaker and less important than any human, the impact of the enemy cannot be trivialized. Jesus said He had to come for the purpose of destroying the work of Satan. (John 3:8; and Hebrews 2:14). Jesus sacrificed much to break the bonds of Satan, didn’t He?