There is a tremendous amount of “hatred” between the Jews and Christians. Catholics have helped perpetuate this hatred by blaming Jews for Christ's crucifixion. And many rabbis have similar hatred towards Christians for blaming them and also convincing Jews to become believers.
Remember that Christ was a Jew and he was a descendant of Abraham, Isaac, Jacob, and David. Can't get more Jewish than by blood.
Until fairly recently, many Christians of all persuasions were guilty of this, not just Catholics. For example, in predominantly Lutheran Germany which contributed to the Holocaust.
Well, no. You can convert. Ruth was a Moabite, but became as Jewish as anyone else.
Many Jewish leaders hated Christians (followers of Christ) long before Christians did anything to them. Read the Gospels and Acts.