If evil can be defined as processes that work against human happiness and natural balance, then we can agree that evil exists and therefore that good also exists, those forces that add to human happiness and natural balance. The effort to live without these notions is a failed experiment, a kind of hubristic aim to eliminate the spiritual effort that is necessary to sanity.
Individual evil, simply put, is a conscious choice to surrender to forces of corruption and human suffering out of fear or laziness. How many of us are innocent in this regard?
One thing I learned from attending 17 years of public schooling is the power of percentages. One can get passing grades, even excel, while making continuous mistakes, even while refusing to let go of particular weaknesses, making up for them with compensatory strengths. The same way of judging academic success is how I look at people, and how much they tend toward evil or good. These judgments may be dangerous, like fire can be dangerous, but in my opinion life without such judgments is a greater danger, one driven by a refusal to submit to reality, or worse a fear of looking at it.
We will advance as a species when we can reenter a public conversation about virtue, one infused with a sophisticated understanding of our past mistakes.