I don't know how to explain this, but nature has no morals. A bear eats fish without having remorse for the fish's family. Morals are based off of emotions (therefore being subjective) as its feeling that something should normally be done a certain way for the better of humanity. 1
The word "evil" is just another in a long list of empty labels used by conservatives in order to dehumanize people they don't want to get to know. Conservatives get hard at the thought of people being punished for being different, and if they actually did some investigation they might find the "others" have good reasons for doing what they do, or perhaps they are mentally ill and would be cured with medication. . . But that kind of thinking takes away from the fun of torturing those lil' piggies!
"Nothing is either good nor bad but thinking makes it so"- Billy Shakespeare......Check and mate! Evil does not exist outside of human perception. What we may perceive as "evil" may actually just be nature! The same can be said of "Sin"! It's all relative man! This was an easy one!
The concept of good and evil, wright and wrong were invented to conceptualize our own natural self preservation especially throughout our existence as a society. A monkey can identify something as good or bad for its own existence such as food which could be perceived as holy (If you took food from one it would certainly act as if you had taken a holy relic from a religious zealot) or a predator which would be viewed as evil and would certainly shy away or avoid such predator as we would a satanic ritual site. All of nature has a way to self preserve, and have similar reactions to things classified to them under the two base categories of good and bad. Animals run from a forest fire just as many Christians run from the hell fire they fear will be unleashed upon them as punishment for deeds seen as unfit to benefit our society (sin). As humans we have a variety of complex layers overlapping with our physical needs as a living organism and our social needs and preservation which is meant to maximize our success in our society. Over time as we developed, our methods of viewing good and bad had to develop as well and in the process got warped by the complexity that we accomplished with our intelligence. So in conclusion I think that the base for what evil is, is a remnant base for our natural process for self preservation that every living organism on the planet has (therefore making it not a solely human concept), but we have warped the idea to fit an almost new paradigm that has a less practical use than the original when looking from a individualist standpoint, however if taken a different stance and viewing it from a social standpoint morals (wether or not they stem from a good/evil outlook) are benficial to the group or society. That is because we've evolved as a society not as the individual.