Evil has a face, just as God does. Just as God's face is seen in humanity, Evil also is seen in human form.
Elie Wiesel in "Night" writes that evil was found in the faces of the Germans who brought them unwillingly to the concentration camps and gas chambers. In the name of "purification", Jewish men, women and children were stripped of all that was human; dignity, respect, choice, family, and life, itself.
What was this evil? It was political, spiritual, and physical. The idea sparked in Hitler's mind, spread throughout the nation of a "purified people", the Arian race, and scapegoated the Jew.
John Wesley opposed what he called "enthusiasm". I believe that this is needed in Christian evangelical circles. Uninformed enthusiasts call for "total commitment" to herald in God's Kingdom. This is nothing new in Church History. People throughout the ages have thought that the "end times" were near and sold all they had to "give to the poor". What is so wrong about this style of "commitment"?
Psychologist would describe those who "set themselves apart", as a "form of "ethnocentric cleansing". Humans love to distinguish themselves from others, as this bring identification. It creates the "I". There is nothing wrong about being different from others, but when there is a dismissing of the "other", then all kinds of atrocities happen. These atrocities have borne the spectrum from political "ethnic cleansing" of the Serbians/Bosnians; the spiritual in the "heresy trials" throughout Church History; and the social, in immigration policy, "gang" formation, or class envy/snobbery.
Whenever humankind has formulated a hierarchal view of itself, mankind has lost in human resources, and lives. Our country's balance of power is a necesary 'balance" to man's inhumanity to man. Checks and balances are needful where there is no "other". Us/Them thinking is a distinguishing "difference", but also can be the beginning of prejuidice. We must not commit acts in the name of any "God", country, people or "cause" that is unreflctive and ignores the "other" in its inception.
This is the beginning of Evil. God warned Cain, that "sin was croutching at the door.