War crimes. In WWII the Germans were guilty of Crimes in Kiev. How can humans be so evil to one another ?

You mean Babi Yar outside Kiev.This happened at most cities,in Russia before about 1943 when the Nazis moved away from shooting in big pits,to the gas chamber system.It was thought by the SS that shooting women and children this way was very dehumanising for the members of the Einsatzgruppen doing the task...not for the actual victims.