<p>I disagree with je-ne-sais-quoi in one minor respect regarding Judaism. Overwhelmingly, all Jewish sects and division agree on the definition of who is a Jew. It’s someone born to a mother who was a Jew, or someone whose status as a Jew has been confirmed by a valid rabbinical court. The American Reform movement now apparently recognizes any child of a Jewish father as a Jew, too, but that is very recent. Of course, differences of opinion may and do exist about what rabbinical courts have been validly constituted, and what standards they should apply. Where the real disagreements come in is with what constitutes a good Jew.</p>
<p>ucsd . . . dad: Saul of Tarsus believed that Jesus was the son of God, and he was Jewish. Your question is a serious one, though. As my previous posts tried to communicate, within Judaism the question of who is a Jew is primarily tribal, not credal. If your mother was a Jew, so are you. Period. If your mother wasn’t a Jew, well, maybe you can jump through 50 hoops over several years and get recognized as a Jew if we get tired of turning you down and you seem crazy enough to have to be Jewish. (That back door doesn’t affect the population count much.)</p>
<p>If you are a Jew, and you believe in the divinity of Jesus, and you talk about it a lot, then you’re a Jew who is saying a bunch of non-Jewish things. If you press it in places like synagogue or a Jewish school, people will probably tell you that you are rude and ask you to leave. (More likely, you will have already left, because it’s more fun to hang with people who support you.) There is an excommunication procedure in Jewish law that I know practically nothing about, because it is essentially unused in the past, say 200 years. I believe excommunication works with regard to a specific community, though. I don’t think any rabbinic court has authority to kick you out of the Jewish people altogether (in part because there’s no central authority).</p>
<p>If you are a Jew who believes in the divinity of Jesus, and who continues to follow Jewish law, then you are a good Jew. That may be oxymoronic – there is some controversy within Judaism whether the notion of the Trinity is really polytheistic. If so, actual belief in the divinity of Jesus would violate the Second Commandment, and that would make you a pretty bad Jew, since worshipping gods other than God is a massive no-no. However, you would probably argue that you were still only worshipping the one God, and everyone would discuss that a lot.</p>
<p>For historical reasons, things like getting baptized and professing belief in Christ do not disqualify you as a Jew, since at various points the authorities liked nothing more than to herd all available Jews into a square, baptize them all, and ask them to choose between voluntary professions of faith and death by fire. However, Jews who really, truly believe in the divinity of Jesus tend to migrate to actual churches where they can act on that belief, and finally get to have Christmas trees, etc. (what every Jewish child wants). So, you don’t hear from them much, and the question of whether they are Jews only matters when someone decides to expropriate and/or exterminate the Jews (in which case the answer is not determined by reference to Jewish law, and is invariably “yes”).</p>
<p>Addendum: “I’ve never been Protestant” is an interesting statement. Protestant ideals are very firmly engrained in American culture. Most Jews I know – i.e., not necessarily the orthodox or Hasids – experience Judaism very much through a lens of Protestant concepts. Myself included. Reform Judaism, which is still very strong in America, was historically conceived to re-imagine Judaism in a way that more resembled Lutheranism, although the pendulum is swinging back the other way in this phase of history.</p>