Who is a Jew according to Jewish law?

Through the mother

The Talmud derives the rule from Deuteronomy 7:3–4, which warns that a son-in-law from the nations “will turn your son away” – calling the daughter’s child “your son”. From here the sages learned that the child of a Jewish mother is Jewish, whatever the father’s identity, and the child of a non-Jewish mother is not Jewish unless converted. The Shulchan Aruch codifies this.

By conversion

Anyone may join the Jewish people by sincere conversion before a rabbinic court: accepting the commandments, circumcision for men and immersion in a mikveh. A convert is fully Jewish and his or her children are Jewish.

Once a Jew

The Talmud teaches: “An Israelite, even though he has sinned, is still an Israelite.” A Jew who stops observing, or even adopts another religion, remains Jewish in Jewish law.

Different movements

Orthodox and Conservative Judaism follow matrilineal descent. The American Reform movement decided in 1983 to recognise a child of one Jewish parent, father or mother, who is raised as a Jew. Israel’s Law of Return uses a wider definition for immigration purposes, while marriage in Israel follows the halachic definition. These differences sometimes make proof of Jewishness necessary – usually through a parent’s or grandmother’s marriage or burial documents.