People don't need much of a reason to hate each oither. Suspicion of the OTHER is hard wired into us, probably since the Stone Age. The Jews had religious differences with their Catholic neighbors, who needed someone to hate when they weren't hating each other. Being "Christ-killers" was the excuse. There are some scholars that think that Christian doctrine fostered this myth (which can be traced back to the Gospels) because the early Christians wanted to keep Roman good will during the Empire, and the Jews were their religious rivals. Christianity split off from Judaism early, during the ministry of Paul, who felt the new religion should include the Gentiles, against the faction of James, who claimed the Christ as a Jewish Messiah.

The Romans hated Jews, back from the days when Jew and Christian were related, practically indistinguishable, and Rome was still recovering from the rebelllions in Palestine. As Rome became Christian, this hatred morphed into hatred of the Jews as the "new" Christians sought to distance themselves from the "old" Jews, and the two religions split. The Christian minority in pagan Rome needed a minority they could afford to hate. This same effect can be seen today as immigrant groups experience prejudice from previous immigrants. It is interesting to note that in the Hellenistic East, or the Muslim empires that followed it, Jews were accepted as the "people of the book", and allowed to live in peace.

I also believe that there is another reason the Jews were hated by their neighbors. The majority peoples around them resented them because the Jews WERE superior. I don't mean racially superior, that's nonsense. They were culturally superior. They were a people that treasured learning and literacy, an urban and cultured people with deep roots in history and an ancient and highly evolved society, a cosmopolitan one. They did not have a heritage of peasantry, they were a civilized people who had prospered everywhere in the world they had settled, no doubt because their culture was so cohesive.

Have you noticed how anti-Semites are always accusing the Jews of scheming to infiltrate the world, to take over and run things, while at the same time attacking them for being inferior and sub-human? How could both of these accusations possibly be simultaneously true?