Nothing Will Come of Nothing
Sin: nothing, something, sort-of-a-thing? Matt raises the excellent question of sin as no-thing (privation) or is it something, he asks? J. R. R. Tolkein followed the main line: Sauron and his evil could never make creatures of his own but could only twist elves into orcs. Evil in Augustine's view is sort of like that: evil comes only as twisted good.
Of course, part of this comes from what seems to be axiomatic in traditional thought: evil cannot be anything because if it is, then God somehow has something to do with it, or it poses itself as a competitor to God's "Godness" (pardon that--it seems to work better in German: Gottes Gottheit).
AC XIX was written in part to show that despite the strong views of God's action in the world, God's creative power, the Reformers did not see that God caused sin in any way. This does not remove the speculative question of how such sin came to be. It wasn't until modern times in which God's "Godness" could be seen more in the light of God making the world out of an already existing chaos or God existing with the world in mutual dependance to some degree.
These latter positions provide occasion to think about something and nothing. In Aristotle's Metaphysics, nothing is not really the sort of nihil that is oblivion. Nothing is sheer potential to be. In that way, there is something in nothing. Aristotle accorded some right to the Pre-socratic mot "nothing will come of nothing" but he saw in nothing only that which waited on becoming something. So nothing is not always nothing. More in this regard would exceed the bounds of a blog post.
As to the devil: is 'he' something or nothing? 'He' gets scare quotes because personal pronouns do not necessarily apply; nor even a proper noun. If the devil is to be accorded reality at all, along the lines drawn by the Bible, he would be a creature. He would be the closest thing to being a creature that has sucessfully refused to be a creature. He has limitless names, and so, cannot be located or pinned down. He will allow himself into no one's gaze or hearing, in order to avoid his own creatureliness.
But despite a short speculative indulgence, the most important locus of Christian speech if not thought on the devil and sin ought best to be its absolution and rejection. For "one little word will fell him."