Is Zionism just supporting Israel's right to exist? In that case I am a Zionist and a Palestinian nationalist too (while seeing Palestinian nationalism as the nationalism of an oppressed people). In fact as a socialist I see myself as an internationalist not a nationalist of any kind.
Was "Zionism actually started with the intention of building a single state where Jews and Arabs could live in harmony"? For sure that was the thought of some Zionists. But there were others who were more hostile to the Arabs, and others more indifferent, no? I oppose demonisation of Zionism, and demonising versions of its history, but I think perhaps you have bent the stick too far the other way.
"The origin of it all is the recognition by a large portion of the Jewish nation in eastern Europe around the 1880's that it was all over." In fact, wasn't the turning point the 1930s, when the revolutionary movements of post-WW1 and the 20s (which didn't just involve a few!) had failed and the rise of anti-semitic movements including Nazism quite understandably pushed the majority of Europe's Jews decisively into the Zionist camp?
"Common in-joke: What is the first task of the Revolution once power has been successfully seized? You purge the Jews of the Central Committee, then the party, then the country." Stalinist states were for sure anti-semitic. Do you think this was true of the Bolshevik revolution? I think you'd be hard pushed to make that argument!
Beyond that, John, you seem - sorry if I'm misunderstanding - to be saying the left can't criticise anything connected to Jewish religion or cultural practices. Eg I for one would criticise circumcising boys! I think it is *possible* to do that while fighting anti-semitism, just as it is possible to criticise cultural practices in Muslim communities while fighting anti-Muslim racism.
As you've noted elsewhere, the AWL has spoken out loudly about the rising stream of anti-semitism.
Lastly: "Student Unions forcing Jewish Student Societies to lower their profiles, and frequent attempts to purge them as such." Do you have specific examples in mind, from now rather than the 80s? If so it would be good to know so we can campaign against this.