The Ari [Isaac Luria] brings this idea that a person can be basically good or even 99% good but have some evil core.

There is evil in quantity and evil in quality. The Ari [Isaac Luria] brings this idea that a person can be basically good or even 99% good but have some evil core. This gives a way to judge people on the scales of merit. For in fact most people that we see are evil simply choose a little less good that their environment would have dictated. Thus even if you see yourself as much better than them, this is only because your upbringing was better. not because you choose better.