Isaiah 14:12-14 (TS2009)
How you have fallen from the heavens, O Helel, son of the morning! You have been cut down to the ground, you who laid low the nations! "For you have said in your heart, 'Let me go up to the heavens, let me raise my throne above the stars of El, and let me sit in the mount of appointment on the sides of the north; let me go up above the heights of the clouds, let me be like the Most High.'

Satan used to be called Helel which means light-bearer or shining one. He was one of the highest ranking angels under God. Until he sinned against God because he wanted to be like God. It's the same kind of sin he used to deceive mankind in the garden of Eden. It is reflected in the world today in which people want to get rid of God and play gods themselves. What else do we know about Satan...

Ezekiel 28:12-14 (TS2009)
Son of man, take up a lamentation for the sovereign of Tsor, and you shall say to him, 'Thus said the Master YHWH, "You were sealing up a pattern, complete in wisdom and perfect in loveliness. "You were in Eden, the garden of Elohim. Every precious stone was your covering: the ruby, topaz, and diamond, beryl, shoham, and jasper, sapphire, turquoise, and emerald and gold. The workmanship of your settings and mountings was prepared for you on the day you were created. "You were the anointed kerub that covered. And I placed you, you were on the set-apart mountain of Elohim. You walked up and down in the midst of stones of fire.

Where else are these precious stones mentioned? In Revelation 21:18-21 these precious stones are found in the New Jerusalem, the Holy City of God in which God's people dwell. Just like Adam and Eve were created to dwell with God in the Garden of Eden this New Jerusalem will fulfill a similar role. It is part of God's plan to replace the corrupted world with a renewed world free of corruption. So Satan as a guardian angel was meant to guard the Holy dwelling place of God and His people, one of the highest ranks of angels. Gemstones are formed underneath the earth by means of heat, pressure and slow cooling. Perhaps the stones of fire refer to the earth's mantle and point to Satan's initial role as the guardian of the earth.

Ezekiel 28:15-19 (TS2009)
You were perfect in your ways from the day you were created, until unrighteousness was found in you. "By the greatness of your trade you became filled with violence within, and you sinned. So I thrust you from the mountain of Elohim, and I destroyed you, O covering kerub, from the midst of the stones of fire. "Your heart was lifted up because of your loveliness, you corrupted your wisdom for the sake of your splendour. I threw you to the earth, I laid you before sovereigns, to look at you. "You profaned your set-apart places by your many crookednesses, by the unrighteousness of your trading. Therefore I brought forth fire from your midst. It has devoured you, and I turned you to ashes upon the earth before the eyes of all who see you. "All who knew you among the peoples were astonished at you. Waste you shall be, and cease to be, forever." ' "

Satan was created perfect and with free will. He fell from perfection when he corrupted his ways and chose to sin against God. He was created to be an anointed cherub which means he was very powerful and of very high status. It was his task to guard the Garden of Eden and likely also Adam and Eve. Satan wanted to be like God and became God's enemy and adversary. His sin was pride. Satan must have first sinned between the creation of the earth Job 38:4-7) and the fall of Adam and Eve. We also know from the story of Job that Satan had access to Heaven after he sinned and played the role of accuser before God.

Luke 4:5-6 (TS2009)
And the devil, taking Him up on a high mountain, showed Him all the reigns of the world in a moment of time. And the devil said to Him, “All this authority I shall give You, and their esteem, for it has been delivered to me, and I give it to whomever I wish.

When the Son of God was tempted in the desert Satan showed Him all the empires of the world. At least since Adam and Eve obeyed Satan instead of God he was given authority by God to rule over this world [spiritually] (Luke 4:5-7, John 12:31, John 14:30, John 16:11, 1 John 5:19, 2 Cor 4:4, Ephesians 2:2). But his rulership is temporary and Almighty God always remains in control ultimately. Satan and his demons wage a spiritual war against God's people (2 Corinthians 4:3-4, Ephesians 6:12). They mislead people by means of for example religion. He is the father of lies (John 8:44). We sure live in a world full of liars. He masquerades as a messenger of light (2 Corinthians 11:14). It is his goal to turn people away from God and draw them to himself.