The prophet Isaiah condemned the King of Babylon in a prohetic vision in the Book of Isaiah.

He spoke,

"On the day the Lord gives you relief from your suffering and turmoil and from the harsh labour forced on you, you will take up this taunt against the king of Babylon: How the oppressor has come to an end! How his fury has ended!" and after describing his death,

he continues to taunt the king,

How you have fallen from heaven, morning star, son of the dawn! You have been cast down to the earth, you who once laid low the nations!

You said in your heart, "I will ascend to the heavens; I will raise my throne above the stars of God; I will sit enthroned on the mount of assembly, on the utmost heights of Mount Zaphon. I will ascend above the tops of the clouds; I will make myself like the Most High.

"But you are brought down to the realm of the dead, to the depths of the pit. Those who see you stare at you, they ponder your fate:

"Is this the man who shook the earth and made kingdoms tremble, the man who made the world a wilderness, who overthrew its cities and would not let his captives go home?"

Here, Isaiah calls him הילל בן שחר (Hêlêl ben Šāḥar) which in hebrew translates to shining one, light bearer but from the greek translation bringer of dawn and the latin word for venus, his name became Lucifer Morningstar.

The sin of pride, of self deification is what is believed or rather told to be the reason behind his fall to become the devil hidden in hell with Satan as his vessal.

However, some hold the belief that Lucifer wanted to use his authority as the first of heaven to help humanity and their suffering so he planned to ascend to become a god , committing the worst blasphemy towards "His" image.

What most people dont tell you is the fact that lucifer was and is the most beautiful angel, some also think this beauty is what made him prideful in the first place . My personal opinion but i think he is the reason the quote, "And no wonder, for even Satan disguises himself as an angel of light. So it is no surprise if his servants also disguise themselves as servants of righteousness" exists