Why were the Ku klux klan so mean?

The first Klan was founded in 1865 by veterans of the Confederate Army. Its purpose was to restore white supremacy in the aftermath of the American Civil War. The Klan resisted Reconstruction by intimidating freedmen and white Republicans, who at the time had a predominantly liberal base Also, the Ku Klux Klan believe that whites are the predominant race, much like the Nazis in WWII. They think they are doing the world a favour by committing genocide o blacks, Jews and other non-Christians.