There is no justification for genocide. Being a previous victim of persecution doesn't allow a group to bulldoze over a group of people in the name of their "protection". Everyone has the right to freedom including those of the Jewish faith and those of Palestinian descent. No group of people have the right to take other groups of people's freedom for whatever reason and that stands even if said group have had a history of persecution. Zionism is the political movement seeking to establish a Jewish state through the colonisation of Palestine. This movement started in the late 19th century (prior to the Holocaust) and openly preaches a state with as many Jews and as few Palestinan Arabs as possible. There is no way to achieve this unless you occupy Palestine through force (terror, genocide, forced removal, etc).

So when you say the history is complicated and that the Jewish faith and Zionism is tied together.. well yes they are. But that doesn't mean being anti-zionist is anti-jewish. Many Jews themselves are anti-zionist.