A few thoughts from a thoughtful reader (I’ve regularized some of the punctuation and uncapitalized the “A” in Atheist for obvious reasons):

Halacha, Jewish religious law, is the only thing that determines Jewish identity. And the issue is very clear indeed, and always has been. The Tanakh tells us that a Jew who adopts any other faith, is an ex-Jew. An Apostate. Now this does not – as in Islam – necessitate nor involve negativity towards this ex Jew. Not at all. But it’s just a statement of fact: a Jew who becomes a Christian = a Christian, just as a Jew who becomes a Muslim = a Muslim.

As for atheism:

Rabbis and Halacha are very clear on this too. Atheism doesn’t involve embracing another, conflicting faith. An atheist Jew, is simply a non practising Jew. Simple as that. Or, if the person prefers not to identity as Jewish, then the atheist is, well, an atheist, who was born into Judaism but has now left. But according to halacha, the atheist is still part of the Jewish family whereas the ex Jew turned Christian, or ex-Jew turned Muslim, is not.

Historically, Jews that converted to other faiths, and then later wished to return to Judaism, had to formally “convert” back to Judaism. I’m slightly concerned that your poll gives the impression that popular opinion can determine who is and is not Jewish. It can’t.

Also, as I’m sure you know, there is a specific Christian Evangelical movement, whose members were never Jews to start with, yet who pose fraudulently as ‘messianic Jews’ and who knowingly lie and misrepresent Judaism and Jews. This group provokes a lot of conflict between Jews and Christians.

For my part, I tend to be skeptical when any debate over Jewish identity is resolved by invoking the overriding authority of halakha. That’s part of what got us into this mess in the first place, and since non-Orthodox Jews are the majority these days (and the source of all that Jewish pride we feel when we talk about Spinoza, Freud, Einstein and Mel Brooks) I think we should have some say in the matter.

There are no easy answers. Nothing is “simple as that” about Jewish identity. Invoking the Tanakh–a collection of ancient Jewish literature otherwise known as the Hebrew Bible–as the fount of all wisdom on matters of personal or collective cultural identity is a push in the wrong direction. We all seem to agree that non-observant Jews are nonetheless Jews, and this fact alone proves the weakness of this argument.

I’m tempted to say that all of this is a matter of opinion. That we celebrate Spinoza (who was given a hearty herem, or  rabbinic excommunication, for heresy from Europe’s most liberal and enlightened Jewish community) as one of our greatest sons only points to the fallability of halakhic law. It is malleable, elastic even, and all it takes is a shift in the way we think about ourselves to tame the once mighty voice of the the Law. God, in the end, is as subject to shifting cultural sands as the marketplace.

From a non-theistic point of view, this all borders on silliness. We know that the Bible was written by men (and likely even women) and believe that there is no supernatural authority whose word is eternal and unchanging. If there were, where is such a word to be found? The Talmud itself would be heretical as it meddles with the Torah on almost every page, adding and subtracting according to the wisdom and convention of the day. Wouldn’t the Torah itself have been enough without the addenda of the prophetic and hagoigraphic books that round out the Tanakh? I hope this brief gloss will suffice to convince the reader that there is nothing simple or clear-cut about Jewish identity.

The poll I posted (Are Jews Who Believe in Jesus Still Jews?) seeks opinions to what is one of the taboos of mainstream Jewish discourse. It does not seek irrefutable answers. Why can a Jew be a Buddhist and not a Christian? Perhaps there is something “conflicting” is the idea of a Jewish-Christian, though the earliest Christians were without exception Jews. So, clearly, this is another cultural-historical construct with no guidelines grounded in religious absolutism. Such is the nature of cultural identity.

We know there are Jews who have embraced Christianity throughout history for various reasons, ranging from personal belief to the threat of death. We also live in a society in which religious and cultural identities are a smorgasbord. There may indeed be excellent reasons why a modern Jew cannot believe in Jesus Christ and still be considered a Jew by fellow Jews (and I believe there are) but let’s not defer our reasoning to the divine think tank to understand why this is so.