In the nineteenth century, religion played a less important role. It was replaced by theories about the differences between races and peoples. The idea that Jews belonged to a different people than the Germans, for instance, caught on. Even Jews who had converted to Christianity were still 'different' because of their bloodline.

The origin of Hitler's hatred of Jews is not clear. In Mein Kampf, he described his development into an antisemite as the result of a long, personal struggle. Supposedly, his aversion to everything Jewish came to fruition when he was living and working as a painter in Vienna (1908-1913). Most historians believe that Hitler came up with this explanation in hindsight. He would have used it to assure people who were not yet convinced of his ideas that they would eventually see the light."