Angels never came down
There's no one here they want to hang around
But if they knew, if they knew you at all
Then, one by one, the angels
The angels would fall
— Melissa Etheridge, "Angels Would Fall"
"Devils... do not differ in nature from good angels, but their nature is depraved. Devil is the opposite of angel only as Bad Man is the opposite of Good Man. Satan, the leader or dictator of devils, is the opposite, not of God, but of Michael."
"When we have understood about free will, we shall see how silly it is to ask, as somebody once asked me: 'Why did God make a creature of such rotten stuff that it went wrong?' The better stuff a creature is made of—the cleverer and stronger and freer it is—then the better it will be if it goes right, but also the worse it will be if it goes wrong. A cow cannot be very good or very bad; a dog can be both better and worse; a child better and worse still; an ordinary man, still more so; a man of genius, still more so; a superhuman spirit best—or worst—of all."
— C. S. Lewis, Mere Christianity Book 2
"You cannot judge me! I am Justice itself! We were meant for more than this — to protect the innocent! But if our precious laws bind you all to inaction...then I will no longer stand as your brother."
— Tyrael, choosing to become a Fallen Angel, Diablo III