God is Lord of light.  Everyone says that.

But that’s not much help to me, since I’m lost in the dark.  If God is going to be my Lord, He has to be Lord of light and dark, death and life.  It’s not enough for Him to have first place in creation.  He has to be the firstborn of the dead, so that in all things He might be preeminent.

Hence the incarnation: The Son took flesh to become Lord of death, Lord of the dark.