The language which they all shared was German, but the people differed on matters of religion, so much so that these differences occasionally erupted into wars between the Catholics and the Protestants.
In those parts of Europe which were occupied by the Nazis, but where these methods of killing large numbers of people had not yet been established, the Nazis assembled large numbers of Jews and machine-gunned them all as they stood on the edge of huge pits which they had dug themselves, or beside natural, deep ravines, as was the case at Babi Yar, in Russia.
In other places, the Nazis herded all the local Jews into the synagogue and then set it on fire.
Throughout World War II, the Nazis devoted considerable thought, equipment, and manpower to the wholesale slaughter of Europe's Jewish population, and by the time the war had ended, they had succeeded in killing six million of them, two-thirds of the total number of Jews in the world.
How could it come about that one nation regarded itself as racially superior to another, to the extent that it felt that it was its right and its duty to kill all the members of that other nation?