Why did the Nazis attack the Jews?

Answer 1

This question implicitly has two parts. The first is a question as to the rationales that the Nazis believed in to justify Anti-Semitic beliefs and the second is a question as to why the Nazis felt the need to kill the Jews as a way to solve these Anti-Semitic concerns.

The Reasons for Anti-Semitism in Germany during that period are numerous, but some of the more important reasons were the following:

1) Decay of the German State: During the 1800s, Jews began to become more integrated in German National Life. They served in its government, its military divisions, and its industry. As was typical of Western Europe, the Jews had more of a hand in the higher echelons of government than their population percentage would account for. The Nazis saw this increasing Jewish percentage in the government as a slow takeover of German policy and a corruption of the German people. They contrasted the great victories under Bismarck with the depressing failure of World War I and noted how a much larger percentage of soldiers in the latter war were Jewish. There was also the sentiment than in the early 20th century, values were beginning to ebb (this is similar to current politics in the United States) and the Jewish integration in the German apparatus (becoming teachers, lawyers, doctors, etc.) was to blame for this recession of values as opposed to modernity as a process.

2) Nationalism: Germany was brought together under the Nationalist conception that all peoples with German culture, history, and language should be united regardless of which principality currently held control. The German self-conception also had an ethnic component, holding that the perfect German was blond and blue eyed. Regardless of the fact that the majority of Germans were dark haired, Jews stuck out like a sore thumb because they overwhelmingly had darker hair. In addition, the idea of a German Jew was still rather new and both Jews and non-Jews tended to see the Jews in Germany as being part of a vast Jewish network and that these Jews just happened to be in Germany. The Nazis capitalized on this cosmopolitan sensibility by claiming that Jews' allegiances were not to the German State, but to secret Jewish Councils organizing world events.

3) Economy: Whether it was true or not, there was perception among Germans and the Nazis in particular that Jews were wealthy individuals and had a higher per-capita income than the Germans. In many ways (because of the above two reasons) Germans felt that the Jews were "stealing" their money while they were poor and suffering.

4) Pseudo-Science: The late 19th and early 20th century was filled with radical new ideas concerning Social Darwinism. It was believed by the Pseudo-Scientific community (which was rather in vogue) that different groups of people or races exhibited different emotional traits that were linked to physical differences. This led to the belief that Jews were corrupt and thieving by their irreversible nature and that they could not be "cured" and brought up as proper Europeans. This formalized Racial Anti-Semitism in Germany and made the situation much more dire for German Jews.

5) Heresy: Although not as much an issue in World War II as it may have been 500 years prior, Jews were still considered the heretics who murdered the LORD and Savior. This helped to justify Anti-Semitism as the Jewish comeuppance for their accepting of the Christ Bloodguilt.

Why was killing the Jews necessary?

The answer to the second part, while cold, is brutally honest. The Nazis encouraged the German population to believe that this myriad of Anti-Semitic issues was ingrained in German Society by making it part of the national curriculum and teaching it to millions of German children. The Nazis proposed that the only way to improve Germany was to remove the Jews entirely. There were two options for such a removal: exile or genocide. Since no country was willing to take the Jewish population en masse (and this includes the United States and United Kingdom due to prevailing stereotypes there) the Nazis made the executive decision to commit genocide to "save Germany".
When Hitler was young, he thought Jews hated him. He believed that because when his mother died, a Jewish doctor was caring for her. So he believed that Jews hated Nazis and that they were no better than rats that lived in the sewers. So he thought they should die for just being Jewish.

Answer 2

Actualy, it was the other way around. Hitler brought up the whole "Jews are the prime evils in this world" idea and the Nazis, being the loyal followers, agreed and carried out his orders the best they could.

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When Hitler joined the party, taking Jews out of society was already in the manifesto.

Answer 3

He didn't, that was the point.