Ask about the story of Satan (if you don't want Baidu Encyclopedia, I hope you can tell it yourself) and about his meaning.

When God created the universe, he created many angels with his free will. Angels can choose to obey God to do good or not to obey God to do evil. The devil is created by God and is an angel with high power. Because of his high power, he became arrogant, competed with God, became the enemy of God, and degenerated into the devil, that is, Satan. The devil also lured a third of the angels to rebel against God, and they became servants of Satan, leading them to sin together with God.