A prejudice against Jewish people is anti-Semitism. Expressing hatred for Jews or refusing to hire someone because they're Jewish are both evidence of anti-Semitism.
The term anti-Semitism is a direct translation of the German Antisemitismus, coined in 1881 to describe the hateful work of a philosopher who believed Jews, also known as Semites were inferior to other groups. Adding the prefix anti-, or "against" to semitism, "characteristic of Judaism," gives you a vile kind of prejudice that led to the death of millions during the Holocaust.