Why? We're all gonna die some day anyway. We're just passing time on this planet for no purpose so, why not murder?
It's not evil as you claim. There is no evil, right? And therefore no good either.
There are simply people and what people do.
I learned these helpful and valuable lessons my beatnik parents.
Perhaps the only reason you restrain your behavior and abstain from brutalizing your neighbors, is fear of eternal torment. If so, I'd suggest that you hold a pretty shallow moral understanding.
As for me, I recognize that any moral claims I may advance pursuant to my own freedom of action, are predicated on my willingness to respect the same claim in others.
As such, I recognize good and evil as objective and unambiguous.