The answer lies in the freedom of choice that God gave to His angelic creatures. God could have created them so that they cannot sin. They would not be able to choose right or wrong because they would be “programmed” to only do right. Had God done this, there would be no meaningful relationships between Him and His created beings. But instead, God created them with freedom of choice so that they could choose to respond to His love and trust Him or choose to disobey. Sadly, Lucifer chose to use his freedom to rebel against God and thus became known as the devil or Satan.
How could the devil who was created perfect go wrong? The answer is pride. “Your heart was lifted up because of your beauty; you corrupted your wisdom for the sake of your splendor” (Ezekiel 28:17). Satan started to think too highly of himself because of all his gifts, he started to crave the honor that was bestowed on God for himself. Isaiah 14 is another chapter that we can draw clues from concerning this and in verses 13 and 14 it says about Lucifer, “For you have said in your heart: ‘I will ascend into heaven, I will exalt my throne above the stars of God; I will also sit on the mount of the congregation on the farthest sides of the north; I will ascend above the heights of the clouds, I will be like the Most High.’”
Lucifer wanted the honor that should only go to the Creator. He wanted it so badly that he was even willing to fight against God for it. Revelation 12:7-9 reveals the fact that there was an actual war in heaven “… Michael and his angels fought with the dragon; and the dragon and his angels fought, but they did not prevail, nor was a place found for them in heaven any longer. So the great dragon was cast out, that serpent of old, called the Devil and Satan, who deceives the whole world; he was cast to the earth, and his angels were cast out with him.”
Satan was cast out of heaven and found a stronghold on earth after he successfully deceived Adam and Eve. Now he, along will all of the fallen angels who are now known as demons (Revelation 20:2) are trying their best to make sure that they deceive as many humans as they can. They want to hurt God, who loves humans and gave Himself for them, and the best way they can do that is to continue the rebellion against Him here on earth and take as many as they can down with them because they know their time is short; they will be destroyed in hell fire (Matthew 25:41). That’s why Peter warns us to, “Be sober, be vigilant; because your adversary the devil walks about like a roaring lion, seeking whom he may devour” (1 Peter 5:8).
Jesus overcame Satan, and Jesus has offered us the help that we need to overcome Satan, too. God is infinitely stronger than the devil. If we unite ourselves with the Savior, we can overcome every sin (Philippians 4:13).
In His service,