On Hating Evil: Searching for the Roots of Moral Malfeasance

I am compiling my thoughts and notes for an essay I hope to write (if my health allows for enough sustained thought) that for now I'm calling, "The Lost Spiritual Art of Hating Evil". The basic question is: why do we (humanity as a species) repeatedly, generation after generation, participate in genocide, mass incarceration, oppression of the poor, racist and/or ethnocentric enslavement and so forth, all the while believing ourselves to be the moral heroes of the story? I feel this is a pressing issue for us as Americans and in particular mainstream American Christians whose self-narrative of righteousness blinds us to much of our history of moral cowardice and outright moral malfeasance.
At any rate, I feel that this quote from Dietrich Bonhoeffer gets very close to the substance of the matter. It is worth noting that Bonhoeffer stands out as a hero because masses of his Christian countrymen from a nation steeped in the Protestant Reformation left him nearly to stand alone while evil rose to prominence.

Dietrich Bonhoeffer - "On Stupidity" from Letters and Papers from Prison