God does not tell us at what point Satan fell from Grace. We first hear about him in Genesis chapter three where man’s fall into sin is recorded. We know that he was created perfect along with all of the angels because Genesis 1:31 tells us; God saw all that he had made, and it was very good. He created all things perfect. Isaiah refers to the fall of Satan in Isaiah 14:12-15 and in it is also recorded in Ezekiel 28;11-17.
In 2 Corinthians 11:14 the apostle Paul tells us; For Satan masquerades as an angel of light. In John 8:44 Jesus rebukes the Jewish leaders for their unbelief and tells them; You belong to your father the devil, and you want to carry out your father’s desire, He was a murderer from the beginning, not holding to the truth, for there is no truth in him. When he lies, he speaks his native language, for he is a liar and the father of lies. God also warns us in 1 Peter 5:8; be self-controlled and alert, your enemy the devil prowls around like a roaring lion looking for someone to devour.
God’s revelation through Ezekiel regarding Satan:
You were the model of perfection, full of wisdom and perfect in beauty. You were in Eden, the garden of God; every precious stone adorned you: ruby topaz and emerald, chrysolite, onyx and jasper, sapphire, turquoise and beryl. Your settings and mountings were made of gold; on the day you were created they were prepared. You were on the holy mount of God; you walked among the fiery stones. You were blameless in your ways from the day you were created till wickedness was found in you. Through your widespread trade you were filled with violence, and you sinned. So I drove you in disgrace from the mount of God, and I expelled you, O guardian cherub, from among the fiery stones. Your heart became proud on account of your beauty, and you corrupted your wisdom because of your splendor. So I threw you to the earth; I made a spectacle of you before kings…you have come to a horrible end and will be no more. (Ezekiel 28: 12-19)