Because the other thread was closed and sent to the rafters for a lot of crap being posted (while I was writing this) I think this overall explanation is useful for people who still have questions about this:
Here's the cliffnote version:
Germany, like many European countries, had always had antisemitism but ironically, up until the end of WWI, Jews looked at Germany as one of the more tolerant places for Jews in Europe. German universities admitted Jews before many in the UK and France (helping create many great scientists) and the leaders of Imperial Germany didn't feel a need to gin up antisemitism for power. They actually hated Catholics and Poles and made them the big scapegoat for some time. There were big exceptions though like Jews couldn't really get promoted in the bureaucracy or German military officer corps.
When WWI hit, Germany was seemingly united, Jew and gentile. The UK Balfour declaration supporting a Jewish state in Palestine was actually in part to win over the sympathy of Jews who didn't really hate Germany. After WWI ended though, it all went to shyt.
Germany lost WWI. There are a lot of reasons why (hint: 2 front war, blockade of raw materials by British) but much of the anger turned within against those who they claimed 'stabbed Germany in the back'. Why Jews though? First, the new Weimar Republic had many prominent Jews and swept away a lot of antisemitism. Second, Germany was suffering since it had to pay war debts and in the hyperinflation and shortages of the 20s, conspiracies about the financial sector, parasites, etc. began to emerge. Walther Rathenau, foreign minister, was a Jew who negotiated a lessening of the debts but did not advocate for Germany claiming it was 'wronged' by the allies and was killed by right wing Jewish youths who believed 'fake news' circulating that his father was a Russian communist.
Some other things were going on too. The Russian Revolution scared middle classes in Europe. Many prominent Russian communists like Trotsky were Jewish. In addition, a group of communists tried a coup in Munich setting up a Soviet Republic and taking hostages. They were led by Rosa Luxemberg, another Jew. They were put down by right wing German paramilitaries, the Freikorps along with German troops. The vast, vast majority of Jews were not communist even though some prominent communists were Jews (actually they were most likely to be self-employed) but propaganda only needs a few good examples to get going. So the Jew=Communist meme took hold. Most Jews voted for the socialist or social democratic parties even though they were capitalists for the same reason most Blacks vote Democrat--all the center right and right wing German parties hated Jews.
Also, because of the Russian Revolution and violence against Jews in the newly independent East European countries, there was massive illegal immigration of East European Jews into Germany where they thought they were safe. Everyone hated them. Even German Jews hated them and were 'embarrassed' by them since they were less educated and more prone to crime (sound familiar?). Albert Einstein actually wrote a public letter to a prominent Jewish organization essentially calling them a bunch of c00ns and fukkboys for abandoning the E. European Jews (Einstein was a Zionist and they generally were more sympathetic like Black Power advocates in our community are more sympathetic to poor Blacks).
Jews became the scapegoat for what was wrong in Germany but Hitler wasn't dumb. At first he said 'only the bad Jews' would be targeted even though he ranted against them all. When he became chancellor, most Jews thought he would need them as part of Germany's economy. Some even gave him tepid support or turned on other Jews hoping they would be accepted (see Fritz Haber's story).
The Nuremberg Laws in the 1930s pretty much segregated Jews and prevented intermarriage like Jim Crow in America. The smart people got out then, many of the rest were eventually killed or nearly killed in camps. The major slaughter didn't start until WWII though. Many historians debate when Hitler actually decided on mass extermination. Is that what his plan always was or did the war put a battery back in another, less lethal plan. There are a lot of books on this.
If you really want to learn about Jews in German society from WWI to the Holocaust, read The Jews of Weimar Germany by John Niewyk. It is worth the read. The comparisons between East European Jews and poor Blacks is a bit haunting. I don't trust c00ns and their optimism partially because of this book.
