Jews self-identify as both a religious and tribal group. Therefore criticism of the tribe is seen as criticism of the religion and criticism of the religion is seen as criticism of the tribe. This is probably most clearly seen in the nuremberg laws, though Hitler's harping on and on about the "Evil" of the Jews was mainly bashing the religion. How, one may ask, is race connected to one's cultural and religious beliefs? it made perfect sense to Hitler and the Nazis, and it makes perfect sense to most Jews.
Real antisemitism does exist, and so does genuine criticism of Judaism, Jewish culture, and Israel. But because those are so interconnected it's difficult to be seen criticizing one without actually criticizing the other. Indeed, it's difficult to actually offer criticism of Israel without also criticizing the Jewish religion on whose basis it rests. It's indeed difficult to criticize the Jewish religion without actually criticizing the Jewish people, whose Jewishness is largely derived from the Jewish religion.
Finally, I don't think there's some magic antisemitic gene floating around, and that Europeans are gradually shifting their phobias over to Muslims.
