When Lucifer was in heaven he occupied the position as the light bearer. Carrying the light of the knowledge of the glory of God and conveyed it to the rest of the Angelic heavenly host for God’s glory. He didn’t just lead the angelic choir into worship, but educated them on the will and purpose of God according to His word.
Hence, he twist the very purpose of the reason of his existence to do the complete opposite of what God had created him for. Due to covetousness and pride of wanting His position.
“Thine heart was lifted up because of thy beauty, thou hast corrupted thy wisdom by reason of thy brightness:I will cast thee to the ground, I will lay thee before kings, that they may behold thee.” Ezekiel 28:17
He became proud in him self because of how exalted God had created him with great beauty, intelligence, gifts and abilities. And dishonestly warped (made strange) his fear of the Lord and the understanding of His holiness through the reasoning of his intelligence out of Jealousy and hatred towards God. Believing that he should be like God, and rule in His throne.
