Why does evil exist?

Sorry for the long absence. I'm afraid the holiday's have taken their toll on my mental productivity.

I was busy looking for a good devotional for use at a church function when I stopped in to read one of R.C. Sproul's latest works on the "Problem of Evil." Naturally, it's a bit too lecturish to use as a devotional, but I thought I could bookmark it by posting it here for your benefit.

Except:

...Though He does not do evil and does not create evil, He does ordain that evil exists. If it does exist, and if God is sovereign, then obviously He must have been able to prevent its existence. If He allowed evil to enter into this universe, it could only be by His sovereign decision. Since His sovereign decisions always follow the perfection of His being, we must conclude that His decision to allow evil to exist is a good decision.

Again, we must be careful here. We must never say that evil is good, or that good is evil. But that is not the same thing as saying, “It is good that there is evil.” Again, I repeat, it is good that there is evil, else evil could not exist...