1.) They believed the Jews had a plot to take over the world and that they were to blame for the German defeat in world war one.
2.) There are more protections in place for those of Jewish descent.
3.) There is often conflict and it is unsafe for Jewish people.
4.) At the end of world war two Israel was declared an independent state. This led to massive jewish immigration. This immigration caused a large relocation of Jewish people, and around 43% of Jews live in Israel. In 1950 under the establishment of the Law of Return Jews born anywhere in the world had the right to become an Israeli citizen. Arabs and Palestinians opposed this, as did other Jewish people because they felt the establishment of a homeland was not essential.