By Adam Smith, Internationalist Socialist League (RCIT Section in Israel / Occupied Palestine), 30.03.2021, http://the-isleague.com
For many years this question has come back to haunt the Zionist state. The many rulings, often contradictory, have shown that this is first and foremost a political question.
The first challenge to the right of return law was in 1962 when a Polish Christian Zionist sought to receive citizenship under the Law of Return law, and was originally denied as he was a Christian, but the Supreme court ruled that he is a Jew from a nationality standpoint (and not from a religious standpoint, so from a “secular” (judicial) point of view what matters is the religious definition, and from a religious standpoint the seculardoesn’t...). After that, in 1970, the law was changed to define Jews as those who were born to Jewish mothers and had not converted. 
The Jewish religion underwent many transitions throughout history. The Judaism of today in Israel is very different from the one in the Diaspora pre-WWII, or from the Judaism in the U.S. today for that matter. In adapting to Zionist chauvinism, the Chief Rabbinate in Israel prohibits Palestinians  and migrant workers  from converting to Judaism (or puts many barriers for Jews from ex-USSR countries), because of fears it is “done for other reasons”. Recently, the Supreme Court has forced the state to accept Reform conversions.
The other way to bypass the Rabbinate Authorities was to be converted during the army - aka “the religion of the tank” as it is aptly put. Of course, during a recent row , a Ultra-Orthodox MK called army converters “Shiksha”, a racial slur for non-Jews. The liberal side went on to criticise him, but by defending the speed up army conversion process. While we oppose the ultra-orthodox racism (and we shall see soon that it is a different side of the same coin), we also oppose the notion serving in the Zionist Army is a good thing, or for that matter, that is makes you a Jew!
The reason the liberal side cares about this, is because there are numerous privileges in Israel for being a Jew, for example the ability to marry in the country, or work in a kosher restaurant - which are the vast majority in Israel (another way in which traditional isolationist orthodox racism combines and blends with the new Zionist racism to form a new kind of religious-nationalist racism, different from both earlier religious orthodox and secular Zionist racisms).
The reform movement in Israel (and the US, although in the US it is more critical of the occupation, with organizations like Jewish Voice for Peace) has many other blind spots with regard to the Palestinian cause. For example, their demand to have equal standing in the Western Wall, while ignoring its history (thousands of Palestinian homes were demolished in order to make way for it, quite different than the propaganda that has always existed in its current form...). Another one is their support for the law of return and Israel in general (a bit a “Liberal” and “benevolent” form of Israel). The material explanation for this is the transition of the Jews from an underclass in the West a hundred years ago (from “No Jew/Irish Need Apply” and the Lower East Side cramped apartments) to the upper middle class in the U.S today,  for example having one of the highest incomes for any ethnic group. 
The law of return was intended to create a demographic shift in favour of Jews in Palestine, and as such, it needs guards to make sure non-Jews don’t slip in, and who better to define who is a Jew in a narrow and ethnic way then the ultra-orthodox? The liberals like to complain that the Orthodox do nothing and get paid a lot by the state. What they don’t understand is that the payment is for their role in expanding the settlements, and maintaining Judaism as a separate and “pure” identity for the Zionist worldview, and guardian of Zionism and the faith.
We call for:
Abolishing the Rabbinate!
A voiding of the racist Law of Return - yes for the right of return for the Palestinians!
Down with the Zionist Occupation!
A one red democratic Palestine (with limited pilgrimage right to the Wailing Wall)!