The unrelenting hatred being manifested by the group Islamic State (and even being excused by some of their supporters and media pundits, as well as the tacit or active support of their brutality by states such as Turkey) is an example of unwillingness to face this aspect of human poison - whether we call it evil or something else.
I bring this up not to point to others but because in clarifying this matter we clarify a fundamental human tendency which we are all subject to and may act out in some forms - unless we practice with this. We are subject to this tendency and reactive habit when beginningless anger "born of body, speech and thought" arises in our life. And it does arise, though hopefully we do not act it out, hopefully in ongoing practice and noticing we do see it for what it is and respond appropriately and as skillfully as we can.
The ongoing killings in Syria by ISIS have overshadowed the long war and brutality of the Syrian government and its allies such as Hezbollah and the Iranian Revolutionary Guard that has killed over 200,000 in recent years. This is the subject of a new exhibit at the United States Holocaust Museum. Below are links to an article and to photos, but be aware of the horrific nature of this matter. Neither "side" in this brutal violence is free of the anger, hatred and resulting brutality.
For me, these events bring up memories of the controversy around the Adolf Eichmann trial. From new research on this in Eichmann Before Jerusalem by Bettina Stangneth we have the following quote from Eichmann,
to tell you quite honestly that if of the 10.3 million Jews . . .
identified, as we now know, we had killed 10.3 million, I would be
satisfied, and would say, good, we have destroyed an enemy.”
An interesting review of this book's findings and an exploration of some of the issues involved in evil and complicity with evil, see: