It seems that most people, whether they be religious or not, believe in something called evil. The problem is, there is actually no such thing as evil because “evil” is really nothing more than an English word we use to label an action or experience which we perceive in a negative way. If nobody had emotions or the ability to feel discomfort or pain then nobody would believe in evil. This goes for good as well, by the way.
One key to understanding all of this, at least from a Christian perspective, is to remember is that evil and sin are two completely different concepts.