Sin and evil are not the same thing. Evil is any deliberate and rebellious action/heart against God. Sin is anything done without giving God glory. Therefore, feeding the poor, taking care of the orphan, or helping the widow, if done without pointing it back to God, is still sin. Yes every good endeavor glorifies God, but the person doing the good work will still be sinning. Thus a nonbeliever doing good in this world is still sinning. Again we have to remember we all start out as evil/wicked beings. We aren't sinners because we sin, we sin because we are sinners. The order matters.