What is the nature of evil? We talk about evil acts (murder), evil people (Charles Manson), evil books (pornography), evil events (tornadoes), evil sicknesses (cancer or blindness), but what makes all of these things evil? What is evil when we look at it by itself? Some have said that evil is a substance that grabs hold of certain things and makes them bad (like a virus infecting an animal) or that evil is a rival force in the universe (like the dark side of Luke Skywalker’s Force). But if God made all things, then that makes God responsible for evil. The argument looks like this:
1. God is the author of everything.
2. Evil is something.
3. Therefore, God is the author of evil.
Augustine vs. Manichaeus
Manichaeus was a third-century dualist who claimed that the world was made of uncreated matter which was, in itself, evil. Hence, all physical existence was evil; only spiritual things could be good. Augustine wrote a great deal to show that all that God created was good, but evil was not a substance.
“What is evil? Perhaps you will reply, Corruption. Undeniably this is a general definition of evil; for corruption implies opposition to nature; and also hurt. But corruption exists not by itself, but in some substance which it corrupts; for corruption itself is not a substance. So the thing which it corrupts is not corruption, is not evil; for what is corrupted suffers loss of integrity and purity. So that which has no purity to lose cannot be corrupted; and what has, is necessarily good by the participation of purity. Again, what is corrupted is perverted; and what is perverted suffers loss of order; and order is good. To be corrupted, then does not imply the absence of good; for in corruption it can be deprived of good, which could not be if there was the absence of good.” [On the Morals of the Manichaens, 5.7.]
The first premise is true. So it appears that in order to deny the conclusion we have to deny the reality of evil (as the pantheists do). But we can deny that evil is a thing, or substance, without saying that it isn’t real. It is a lack in things. When good that should be there is missing from something, that is evil. After all, if I am missing a wart on my nose, that is not evil because the wart should not have been there in the first place. However, if a man lacks the ability to see, that is evil. Likewise, if a person lacks the kindness in his heart and respect for human life that should be there, then he may commit murder. Evil is, in reality, a parasite that cannot exist except as a hole in something that should be solid.
In some cases, though, evil is more easily explained as a case of bad relationships. If I pick up a good gun, put in a good bullet, point it at my good head, put my good finger on the good trigger and give it a good pull … a bad relationship results. The things involved are not evil in themselves, but the relationship between the good things is definitely lacking something. In this case, the lack comes about because the things are not being used as they ought to be. Guns should not be used for indiscriminate killing, but are fine for recreation. My head was not meant to be used for target practice. Similarly, there is nothing wrong with strong winds moving in a circle, but a bad relationship arises when the funnel of wind goes through a mobile home park. Bad relationships are bad because the relationship is lacking something, so our definition of evil still holds. Evil is a lack of something that should be there in the relationship between good things.
 Geisler, N. L., & Brooks, R. M. (1990). When skeptics ask (pp. 60–61). Wheaton, IL: Victor Books.