To understand the Left, one must understand that in its view the greatest evil is material inequality. The Left is more troubled by economic inequality than by evil as humanity has generally understood the term.
Most blacks want school vouchers, but most liberals vehemently oppose them. Why? Because what is good for teachers' unions is of more importance to the Left than what is good for blacks. Who, then, is racist? By their own admission, and by the policies they pursue, the answer is the people who call themselves progressive.
Therefore the vast majority of the people who affirm leftist beliefs think of their views as the only way to properly think about life.
Goodness is about character - integrity, honesty, kindness, generosity, moral courage, and the like. More than anything else, it is about how we treat other people.