Is evil only ever passive (absense of good)?

In her chapter titled “Maker of Ill Things”, Sayers tackles the tricky question of where evil comes from. Focusing on her angle of “God as Creator” she gets right past dualism and get’s straight to the fact that God DID create evil and even the person of the devil (because he created everything). However, she takes the angle of “evil has no reality except in relation to his[God’s] good”. This is just an a little scrap of it here, but I think she does a pretty good job of explaining this position without getting knee-deep in philosophical jargon.

…we may make an attempt to tackle the definition of Evil as the deprivation or the negation of the Good. If Evil belongs to the category of Not-Being, then two things follow. First: the reality of Evil is contingent upon the reality of Good; and secondly, the Good, by merely occurring, automatically and inevitably creates its corresponding Evil. In this sense, therefore, God, Creator of all things, creates Evil as well as Good, because the creation of a category of Good necessarily creates a category of Not-Good. From this point of view, those who say that God is “beyond Good and Evil” are perfectly right: He transcends both, because both are included within His Being. But the Evil has no reality except in relation to His Good; and this is what is meant by saying that Evil is negation or deprivation of Good.

-Dorothy Sayers, The Mind of the Maker, Ch.7

I’m not quite sure if I find this concept completely convincing or not. It seems like a non-answer to some of the deepest questions about evil. I guess it’s OK though. You could do a lot worse. I like better her version of the conversation between Faust and the devil:

FAUSTUS: Who made thee?
MEPHISTOPHELES:God, as the light makes the shadow.
FAUSTUS: Is God, then, evil?
MEPHISTOPHELES: God is only light,
And in the heart of the light no shadow standeth,
Nor can I dwell within the light of heaven
Where God is all.
FAUSTUS:What art thou, Mephistopheles?
MEPHISTOPHELES: I am the price that all things pay for being,
The shadow on the world, thrown by the world
Standing in its own light, which light God is.

-Dorothy Sayers, The Devil to Pay