Observing the absurd rules of Shulhan Aruh, which were antiquated from their inception, doesn’t make a Jew. Almost no proselytes study Jewish philosophy and theology. Historically, conversion was a momentary formality for entering the Jewish way of life which includes not only orthopraxy but also the expectation of dying from anti-Semitic violence and suffering anti-Semitic attitudes.

Modern conversion is a sham, but some kind of conversion was always there. The crowd which joined us in Exodus, were foreigners who settled in Samaria and turned to a kind of Judaism. Idumea was converted, as were many proselytes who historically joined the Jews. Defining Jewishness through bloodline is tempting, but doesn’t square with practice. It’s not self-evident that a Jewish great-grandmother alone makes one a Jew.

Torah curses idolaters until the fourth generation because those are the furthest descendants who could know the idolater. Similarly, living a Jewish life for four generations makes a family Jewish. Third-generation descendants of the Egyptians enter the people of Israel automatically (Deuteronomy 23:9); similarly, grandchildren of Slavic spouses should be considered Jewish because the Jews lived among those nations like among the Egyptians. The Torah’s logic is plain: the grandchildren of the Egyptians were granted “citizenship” because Jews had lived in Egypt, and thus intermarried a lot. The Egyptian spouses joined the Jews in Exodus for a better future, just like the Jews’ Slavic spouses move to Israel now. Asking them all to formally convert was unrealistic, and the Torah deals with intermarriages on a de facto basis—regulating rather than forbiding, like it (over-)regulates slavery. The Deuteronomist allowed the mixed Jewish-Egyptian marriages to stay with the provision that only their grandchildren—already available by the time the Deuteronomy was written—be recognized as fully Jewish. Gentile spouses could eschew the second-class status of ger, or God-fearer, through giyur.

A major scriptural condemnation of intermarriage is in Nehemiah 13:23-30. The paragraph is a late addition, following the completion at Nehemiah 13:22. Even so, the author only condemns intermarriage with demonstrably alien Ammonites and Moabites. Though the concern about foreign spouses driving the Jews away from Judaism is legitimate, the Deuteronomic rule of assimilating foreigners who live with Jews for three generations is sensible. Modern Israel could reject half a million Slavs, but short of expulsion they would still slowly intermarry Israeli Jews, flooding the Jewish country with non-Jews and ending the Jewish familial lines. Under the currently stringent terms of giyur, tens of thousands of Jews in each Israeli generation who marry Slavs will produce no Jewish offspring. Alternatively, Jews could apply the Deuteronomistic reasoning, and automatically accept grandchildren of mixed marriages in Israel as Jewish.

Self-identification as a criterion rejects masses of assimilated Jews who don’t identify themselves with the Jewish nation to any degree. It’s evidently unfair to bar their children from becoming Jews.

Possibly, a Jew needs to fit any of several criteria: descend from two Jewish parents, or from a Jewish parent and a spouse who identifies with the people of Israel, or accept Judaism formally and beyond doubt. Controversially, one could enter the Jewish nation as a sort of honorary citizen by an immense contribution to the nation or state, such as fighting for the Jewish cause. Such a definition could satisfy atheist nationalists, but emasculates the Jewish raison d’etre. There are thousands of tribes and nations on the face of the Earth; being one of them is no achievement for Jews, and not wroth displacing the Arabs. Jews are important only as a beacon to nations, as bearers of the Jewish idea. What good is it to be a Jew against all odds, if not for serving God and shining light on the world? Jews are better defined as a hardened group which carries on the ideals of the Torah. “Hardened” means that one does not leave it by choice; assimilated Jews still retain a metaphysical attachment to the Jewish nation, enough that their children could be explicitly Jewish. As with the idolaters, four generations of rejecting the Jewish idea strips their descendants of Jewishness. For practical purposes, no one feels a Jew just by having Jewish great-grandfather. Gentiles could join the Jewish nation immediately, as a matter of choice, provided they demonstrate commitment by any means, religious or nationalist. But a well-wishing Gentile is still not Jew. For four generations, proselytes have to demonstrate strong personal commitment to Judaism. Proselytes’ children who turn to Christianity or atheism, or refuse to fight for Israel, are not Jews. After four generations of demonstrated commitment to Jewishness, proselytes’ descendants could be safely pronounced Jews. Their children retain Jewishness regardless of their level of commitment.

The guidelines could be summarized thus: Jews are the people who demonstrate doubtless adherence to the Jewish idea, and the people who do not adhere but have at least one Jewish great-grandparent. That could theoretically dilute the Jewish nation with people whose genetic relation to Jews is very remote. In practice, only people who strongly identify themselves with the Jewish idea would claim Jewishness based on their ancestral connection; others won’t care about their Jewish roots. The fourth-generation criterion will boost the nation’s size with many committed Jews whose children will be Jewish even by religious standards.

But decent Jews prove their commitment to Jewish values every moment of their lives.