A close inspection of verses 13 and 14 provides some more insight. Apparently Lucifer was in Eden and was arrayed with fine stones and gold. It also says that God had appointed (“I set thee so…”) Lucifer as an anointed cherub that covereth. This would suggest that he had some kind of authority.
So, here is a being who was perfect--amazingly so. God had bestowed on him authority, great beauty, and wisdom. So what was it that was his undoing? It’s in verse 17. There’s no mistaking it--Lucifer was blinded by pride. This makes Lucifer not only the origin of sin but, also, the original sinner.
Although Ezekiel opens the verses speaking of the ruler of Tyre, there is no mistaking that he immediately launches into an event that occurred in the spiritual and has made its’ way into the earthly realm. It’s obvious in verse 17 that Lucifer had possessed wisdom but perverted it. The Bible says that it was by reason of his brightness. Lucifer had ceased to love his God (creator) and had started elevating himself.
Isaiah 14:12 through 15 renders more insight into the thinking of Lucifer. In verses 13 and 14 he says “I will” five different times about what he is going to do. From this it is easy to understand how the ‘light-bearer’ became Satan, the Adversary. He conceived a lie in his heart. He took the gifts that God bestowed on him and used them in acts of defiance. God has said how he will deal with him. It’s an eternal doom that none of us want to share in.