Good and evil all depends on moral boundaries. If something is considered immoral by the general population then it tends to be evil. I think the more people that consider something as being immoral the more "evil" it tends to be branded (eg killing someone). Whereas something that is believed to be very moral (eg donating to the poor) by a large number of people tends to be considered "good". All depends on someones moral boundaries.

If someone were to murder another without their morals interluding(By that I mean someone murdering someone else without the little voice in the back of their head saying "No thats wrong") then that person would consider what they did as being morally right whereas others would condemn such activities. Someone who is considered to have the wrong morals tends to be defying the general populations view on morals.
So in my opinion there is no such thing as right or wrong only what an individual percieves.