I believe that evil is merely a prerogative based view point.
Some one that I see as evil may see me as evil just the same. So who would be the evil one then? Do we go to a consensus to determine this? Can popular opinion truly define the details of evil?
It is my belief that there is merely what is good for us and what is not. It should be our goal to strive to do what is good for us. We can not act on the behalf of others without their consent for fear of a misunderstanding due to everyone having their own perspective. Therefore it is best to act on what is in our best interest, that also does not impede upon others.
This is not to suggest that we should be cold to others. I am merely suggesting that we apply empathy before action. We must try to see things from the perspective of others if we wish to do anything for them.
The most important idea I wish to impart is that people are inherently neutral and are not inherently "evil" or "good". We do what we must to survive and thrive. All people carry value in existing even the most despicable. This is also why I believe that atonement is a better sentiment than demise when seeing an "evil" person held for their "crimes".
Having said all of this there are always outliers. Those that do not fit within the scheme or normal reasoning. Those that are irreparably damaged or broken. Through no fault of their own they came to be something that no longer resembles a human; a monster. They perform acts that carry no true benefit toward survival or a bettered existence. I do not wish to describe these things for we would all balk at the thought of them; even the incarcerated find them in poor taste to put it flatly.
Those with all their faculties should not allow the perspective of burden to place weight on their shoulders. When acting with others effected, empathy should be applied.