Level: Basic
A Jew is any person whose mother was a Jew or any person who has gone through the formal process of conversion in full compliance with Jewish law.
It is important to note that being a Jew has nothing to do with what you believe or what you do. A person born to non-Jewish parents who believes everything that Orthodox Jews believe and observes every law and custom of the Jews is still a non-Jew, even in the eyes of the most liberal movements of Judaism, and a person born to a Jewish mother who is an atheist and never practices the Jewish religion is still a Jew, even in the eyes of the ultra-Orthodox. In this sense, being a Jew is more like a nationality than like other religions; it is like a citizenship.
Although all Jewish movements agree on these general principles, there are occasional disputes as to whether a particular individual is a Jew. Most of these disputes fall into one of two categories.
First, traditional Judaism maintains that a person is a Jew if his mother is a Jew, regardless of who his father is. The liberal movements, on the other hand, consider a person to be Jewish if either of his parents was Jewish. Thus, the child of a Jewish father and a Christian mother is a Jew according to the Reform movement, but not according to the Orthodox movement. The matter becomes even more complicated, because the status of that child's children also comes into question.
Second, the more traditional movements do not always acknowledge the validity of conversions by the more liberal movements. The more modern movements do not always follow the procedures required by the more traditional movements, thereby invalidating the conversion. In addition, Orthodoxy does not accept the authority of Conservative, Reform, and Reconstructionist rabbis to perform conversions, and the Conservative movement has debated whether to accept the authority of Reform rabbis.
In March, 1997, the Agudath Ha-Rabonim issued a statement declaring that the Conservative and Reform movements are "outside of Torah and outside of Judaism". This statement has been widely publicized and widely misunderstood, and requires some response. Three points are particularly worth discussing: 1) the statement does not challenge the Jewish status of Reform and Conservative Jews; 2) the statement is not an official statement of a unified Orthodox opinion; 3) the statement was made with the intention of bringing people into Jewish belief, not with the intention of excluding them from it.
First of all, the Agudath Ha-Rabonim statement does not say that Reform and Conservative Jews are not Jews. Their statement does not say anything about Jewish status. As the discussion above explains, status as a Jew has nothing to do with what you believe; it is simply a matter of who your parents are. Reform and Conservative Jews are Jews, as they have always been, and even the Agudath Ha-Rabonim would agree on that point. The debate over who is a Jew is the same as it has always been, the same as was discussed above: the Reform recognition of patrilineal decent, and the validity of conversions performed by non-Orthodox rabbis.
Second, the Agudath Ha-Rabonim is not the official voice of mainstream Orthodoxy. Their statement does not represent the unified position of Orthodox Judaism in the US. In fact, the Rabbinical Council of America (the rabbinic arm of the Union of Orthodox Jewish Congregations of America) immediately issued a strong statement disassociating themselves from this "hurtful public pronouncement [which] flies in the face of Jewish peoplehood".
Finally, before one can denounce a statement like this, one should make an attempt to understand the position of those making the statement. According to Orthodoxy, the Torah is the heart of Judaism. All of what our people are revolves around the unchanging, eternal, mutually binding covenant between God and our people. That is the definition of Jewish belief, according to Orthodoxy, and all Jewish belief is measured against that yardstick. You may dispute the validity of the yardstick, but you cannot deny that Conservative and Reform Judaism do not measure up on that yardstick. Reform Judaism does not believe in the binding nature of Torah, and Conservative Judaism believes that the law can be changed quite flexibly.
The Agudath Ha-Rabonim did not intend to cut Reform and Conservative Jews off from their heritage. On the contrary, their intention was to bring Reform and Conservative Jews back to what they consider to be the only true Judaism. The statement encouraged Reform and Conservative Jews to leave their synagogues and "join an Orthodox synagogue, where they will be warmly welcomed". Some Orthodox and Chasidic Jews believe that if there were no Reform or Conservative synagogues, everyone would be Orthodox. It seems more likely, however, that if there were no such movements, most of these people would be lost to Judaism entirely.