Of course it is a chestnut that Hitler killed them by himself. Eichmann, one of his subordinates, pleaded that he was only following orders. The Nazi government was a social machine. It conducted the war and it conducted the extermination camps.
But, most importantly, hatred of the Jews was nothing new in Germany with Hitler. The relation between Christian and Jew in Europe had always varied between best of friends and mortal enemies. And it didn't seem to stem from the actions of the Jews. Complicating matters, the Jews were essential because of their business skills and answered directly only to the King. This no doubt led to resentment by the commoners, who were oppressed by authority at every turn. The Jews stood as a state within the state, a stateless people and the difficulty with this dependency is what led to a solution in the creation of a Jewish state,Israel.