The first problem is that we don't have a good definition of Evil. It seems situational, relative to our surroundings, arbitrary, and subject to interpretation. Folks who do nothing but sit around and think about these things trace the origin of Evil to the Creation Myth stage of human development. They suggest that Evil comes from 2 different sources. One comes from a titanic struggle between Good and Evil, where Good is represented by creative forces, loving forces, compassion, caring, etc. Evil is destructive, hating, death oriented, trouble-making, and opposed to the Good in some fundamental way. The second is that Evil is on one end of a spectrum of existence, and Good on the other. Every act, everything that happens, can be placed on a continuum of Good and Evil, and at some point we can say that things below this line are Evil, and above this line are Good. There are lesser and greater Goods, and lesser and greater Evils.
Is Evil pain and suffering, or can Evil be not being able to find a parking space when you need one? Is bad luck Evil? Is good luck Good? Is Evil an innate feature of the human condition? Freud thought so, calling it the Death Drive, and attributing to the human character a battle between Love and Death. Having lived through Nazi Germany (yes, I invoked it!) as a Jew, Freud was convinced that the Death Drive was alive and well in the human psyche and could not be suppressed.
I just read Hear of Darkness by Joseph Conrad. Published in 1902, this book describes the mentality of European colonialists who are seeking fortunes in the Belgian Congo in the 1880's and 1890's. The conditions of depravity and suffering by the natives at the hands of the Europeans, and from the ravages of disease in the Congo are appalling and certainly warrant the title of Evil. The demented condition of Mr. Kurtz, the pivotal character in the book who "goes native" in order to secure the greatest amount of ivory the company has ever seen, reflects on his condition and what he has seen and mutters, "The horror, the horror..." on two occasions, hinting at the extent of Evil that he has seen, and has created with his actions. He certainly seems Evil, but can his actions be judged without putting them into context? Are the inhuman acts that take place between the natives as a normal part of their culture any less Evil? After all, this would seem to be Man in a natural condition, would it not?
Evil is a problem. What is it? How can we define it? How can we elevate it to a status of more than a superficial black-and-white comparison between Good and Evil?