There is this idea that Jews were chosen by God to widespread his word - the chosen nation. I don't know how it is now, but there was a time when Jews really represented themselves as the chosen ones and of course others didn't like that. The second and the most important reason is the non-recognition of Jesus as the son of the God. European and American cultures are based on Christian values, so even atheists living in Europe or in America are part of this Christian culture and identity that from the crucifixion of Jesus has kept this antipathy towards Jews. This antipathy lies in the essence of our culture