Just responding to the original argument here... haven't read the rest yet. My apologies if this has already been mentioned. The Jews were the money lenders throughout European history from the dark ages to the time of Hitler. Christian doctrine actually forbade the lending of money for interest, or so they believed in earlier times (not so much today, for some reason).
So, the Jews were the loan sharks of Europe... do you see why that might make some people a bit hateful of them?
Anyway, that's one of the causes. Actually, that role of Jews in Europe kind of kept them from "blending in."
(added) And yes, I realize that not all Jews in Europe were money lenders. However, the society tended to be a bit segregated, and the primary reason that your common Joe might have had contact with a Jew would very likely have to do with his needing money.