What exactly is sin? If you asked ten different people, you might get ten different answers. Some might say that sin is “doing something wrong or breaking the law,” while others might say that sin is “hurting another person or taking an innocent life.” Still others might deny the very existence of sin, saying that there is no such thing as right or wrong– in short, that there are no real absolutes in this world. However, most people agree (regardless of culture) that there are certain actions that are wrong, and should be punishable by fines, imprisonment or even death.
Even the person who “doesn’t believe in right or wrong” would have a hard time observing a maniac rape and murder a small child, and say that what happened to them was not a crime.
Sin is a terminal disease that eats away at the very heart of this planet. It destroys individual people, families, cultures, even the earth itself.
You can read all of this article, "What the Bible Says About Evil in the World" at http://bibleresources.org/evil-in-the-world/