There was a long tradition of anti-Semitism in Austria and Germany. Hitler acknowledged his debt to Chamberlain, Luger (a mayor of Vienna), Schonerer and Lanz. And after the early persecutions of trade union and socialist leaders, the flagbearers of opposition were either dead or in concentration camps.
Nor was there an outspoken non-conformist church in Germany. The Lutheran church was a state church and split into Deutsche Christen (Nazi) Bekenntniskirche (opposition) and a silent majority.
The Catholics had signed a concordat with Hitler and helped to vote him into power. Some priests spoke out against the euthanasia programme but few criticised anti-Semitism.
Few Englishmen appreciate what totalitarian terror means. Every day Germans were executed for listening to foreign broadcasts. Strict censorship meant that few knew what was going on in the camps.
But there was another component - not exclusively German. On Channel 4's Birds of Death, several decent-looking ancient RAF pilots were asked why they had machine-gunned Kurdish women and children in the 1920s. Their reply? Because they were Kurdish, because the women couldn't shoot back and because holding a machine gun gives you a sense of power.