I had previously believed that the antisemitism was a relatively new thing to the western world during the events of World War 2, and that those kinds of beliefs didn't really manifest themselves in powerful ways before then anywhere other than the middle east/near Israel. Today I learned about how Martin Luther was a pretty avid jew-hater, and heard some choice quotes of his, which has opened my eyes to the prevalence of the viewpoint that I hadn't known about.

My question is this: where did these antisemitic views come from? How did they become so popular? How have people rationalized their hate for Jewish people over the years?