the legend of lucifer

It was pride that changed angels into devils; it is humility that makes men as angels. ─Saint Augustine

According to ancient Christian legend, God created the angels to worship and to serve Him.  Then, after he had begun the creation of our world but before the creation of human beings, God granted the angels a vision not only of humankind but of Christ.  And God commanded the angels to serve humans and to worship the Christ.

To the angels, this was a strange command -- that they, pure spirits, should so defer to beings lesser than themselves, creatures mingled with matter.  

Now it happened that of all the angels God created, the most beautiful and most brilliant was Lucifer, the "light-bearer."  This greatest of the angels, immersed in his genius and enamored of his beauty, refused God's command, declaring:  "I will not serve!"

And so God banished Lucifer and the angels who followed him from Heaven and they became "the bad angels" called "devils."