Most Jews in post-WW1 Germany, and especially those in prominent positions, had dim views of traditional Jewish culture and were not religious at all.
Even so, the nationalists projected their hatred against them. Walther Rathenau was one such prominent politician and statesman of Jewish descent, who wasn't religious at all and was one of those 150% nationalists. They still assassinated him, without even a concrete reason. His prominence made him a lightning rod for other peoples' frustration and that was enough to have him killed.
Here's a bit of text I posted shortly ago
in another thread, on the topic of antisemitism, and how it is *not* a reaction to anything Jews do or did:
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As paradox as it may sound - antisemitism is not about "getting even" with the Jews. Antisemitism is all about expurging the civilized, restrained, well-articulated, easily adaptable, nuanced, sceptic, well educated, non-dueling, non-violent, non-virile, non-aristocratic, cosmopolitan urbanite, and raising in his place the masculine, aggressive, simple-minded, unrefined, brutish, rooted-in-the-soil, farmer-soldier type who nurtures his self-esteem not by thinking highly of his own abilities, but by pondering what a prestigeous man (or cause) he serves.
Wherever you have a social
milleu that is characterized by strict loyalty structures, virile values, and an emphasis on not-doubting, not-questioning, and letting others make decisions for you, you have an environment which is a potential breeding ground for antisemitism (in this particular time period, i.e., 1900-1940s).
Antisemitism is not a reaction to Jews, it's a reaction to the challenge that the modern, intellectual, anti-aristocratic, uninterested-in-the-past lifestyle poses to people whose were raised on the opposite values. Socialism and Communism are exactly that sort of challenge, they are an attack on the traditional values by a modernist movement with the stated intent of "rationalizing" society and "correcting" all the injustices caused by traditional social structures.
Historically, antisemitism only really disappeared when societies finished the social and mental "modernization": The leaving-behind of the old 19th century values, the disappearance of aristocracy and aristocratic structures, the complete eclipse of the rural lifestyles by urban life styles, and the reformation of the political system into a system centered on the values of dialogue, non-bellicosity, and compromise. The USA never got antisemitism because they were founded on those modern values already way back in the 18th century. Britain largely left it behind at the turn of the 20th century because the whole 19th century was one huge mental and social modernization push for them. Germany only left it behind after 1945, thanks to being shattered and then reassembled with completely new (American) values. In much of Eastern Europe, they only really left it behind in the 1980s-1990s.