On Quora this question was posed. My answer:

What role did Nazi propaganda play in reinforcing Hitler's negative stereotypes about Jewish people?

Hitler did not need “propaganda” to reinforce his negative stereotypes about Jewish people; he was already against them by the time he joined the NSDAP. Mein Kampf details his journey from finding course anti Jewish thought to be ignorant and odious to accepting that Jewish is an ethnicity and not a religion.

That one thought is what influenced him more than anything. Hitler was correct in that the Ashkenazi were a foreign people, but he had little understanding of the various kinds of Jews and their heterogeneous origins, incorrectly assigning Jews as a whole were an ethnicity rather than different ethnicities united by a religious heritage.

What Hitler saw was the over representation of mostly secular Jews in the Communist, anti war (WWI) movements, media, academia, and banking. His only conclusion was that the Jewish people were a foreign people within Germany pursuing their own agenda which was incompatible with German objectives.

Probably the deepest wound for Hitler was the Jewish anti war effort. Germany was extremely pro Jewish before and during the war. When Jewish union leaders organised strikes at armament factories, hurting the war effort, and Jewish ran newspapers in America completely flip flopped on the issue of America entering the war and whipped up a war fever (mostly based upon lies) after the Balfour Declaration, it became obvious to many that the Jews turned on Germany. That sense of betrayal fed a lot of anti Jewish sentiment and the feeling that Jews weren’t Germans of a different religion but a foreign people within their own interests.

There are other examples which Hitler cites in Mein Kampf as pushing his radicalisation. One was the formation of the Bavarian Soviet Republic in 1918 with the Jews Kurt Eisner (who also organised the strikes at the end of WWI) and Max Levien. The Jewess Rosa Luxemburg also infamously was involved in another revolution tearing apart the German nation. These are all meticulously cited examples in Mein Kampf and ones which all Germans knew and understood.

The only thing the NSDAP had to do was convince the average citizen that Jews were a distinct ethnicity rather than fellow Germans. While nobody today really questions that being Jewish is a genetic identity rather than a religious one, before Hitler’s rise that was hotly debated and denied by many leading German Jews (Marx himself ridiculed Judaism and Jews despite being ethnically Jewish himself). That is why we see a lot of German propaganda about the physical characteristics of Ashkenazi Jews. The people already saw negative actions by Jewish people, nothing had to be invented or whipped up, they just had to be convinced of WHY those Jews committed those acts.

Nationalism provided that answer- they were not Germans. Civic nationalism is a very recent development. Even in America being “American” meant being of a particular race (see Who Are We? The Challenges to America's National Identity By Samuel P Huntington). In the late 19th century and early 20th century ethno nationalism was all the rage in Europe and nationalist movements arose from Ireland to the Balkans. It was an easy transition to go from understanding that Ashkenazi Jews were Germans of a different religion to Ashkenazi Jews being a distinct nationality within Germany working for its interests against Germany’s. Itmade sense to the milieu of early 20th century Europe. The emphasis on the different physical characteristics of Jews seems quite crude today but they fit perfectly well with the mentality of the day and the purpose the NSDAP was pursuing.

One need only to read the NSDAP party programme to get an understanding of the mindset. The NSDAP were firmly in the nationalism of the day and sought a state which was run for and by ethnic Germans. Again, this was a common thought across the West, even in America. Polish nationalists persecuted ethnic Germans for the same reason, they did not belong in the state, they were not of the nation and had rival interests (which is why FDR created camps for Japanese, German, and Italian citizens in America, those of a hostile nation were suspect even if they held citizenship). The main thrust of NSDAP “propaganda” wasn’t inventing crimes to accuse Jews of but to establish that they were not German.