An angel in one's own eyes.

"God should be praised and blessed forever for dealing with His saints in a truly wonderful manner. For while He permits them to be weak and to stumble, while He lets them abound with actions that result in displeasure and offense, and the world judges and condemns them, He forgives them these weaknesses and has compassion on them. On the other hand, He leaves to Satan and utterly rejects those who are angels in their own eyes." -Luther on Genesis 9:20-22 (LW 2:169)