Snubbed by Zion - Israelis seem to have little regard for diaspora Jews.

The move was a startling one, even shocking, asserting the supremacy of certain Israeli Jews by, in effect, demeaning the legitimacy of their American co-religionists. And it was done without consulting the American rabbinate, catching American Orthodox rabbis completely off-guard. The move rests on a dual assumption: There should be a world-wide uniform standard for conversions, and the official Israeli rabbinate should be the body to determine it.

Understandably, American Orthodox rabbis resent suddenly finding themselves in the same category as Reform and Conservative colleagues, whose converts have never been recognized by the Israeli rabbinate. Others feel that, by seeking to represent not just Israel but the Jewish people, the Israeli rabbinate is attempting to overturn a millennia-old de facto pluralism born of the diaspora. Jewish peoplehood, they note, was never threatened by the fact that the Jews of Warsaw, for instance, adopted very different standards of Jewish law from the standards of the Jewish community in Baghdad.

The Israeli rabbinate, turning away from this model, cites Isaiah's prophecy as the justification: "For the Torah will go forth from Zion, and the word of the Lord from Jerusalem." American rabbis now fear that their Israeli counterparts believe that the return to Zion entails a return to a monolithic Judaism. One American rabbi told the Israeli newspaper Ha'aretz that the new edict gave the impression "that Rabbi Amar is trying to become a sort of Jewish Pope."

Naturally, the new policy affects not just American rabbis but also the laypeople who have spent years preparing to become committed Jews. Rabbi Seth Farber heads an agency here called Itim that helps individuals navigate the often maddening Israeli rabbinic bureaucracy. He says that the decision has "sown panic among hundreds if not thousands of Orthodox converts overseas."

The Chief Rabbinate's move is best seen against the broader backdrop of the shifting relationship between Israel and the diaspora. In recent years Israeli Jews have begun to answer what they perceive as the paternalism of American Jews--whose financial and political support have greatly contributed to the country's well-being--with a little paternalism of their own.

One reason for Israel's new brashness is demographic. Israel's Central Bureau of Statistics announced last month that 5.64 million Jews live in Israel. For the first time since antiquity, there are more Jews in Israel than in any other country.

But another reason that Israelis increasingly think of themselves as the central agents of Jewish history has more to do with ideology. This notion was thrown into high relief by another recent case of Israeli conceit scandalizing American Jewish vanities. The very day that the population numbers were announced, the well-known, secular Israeli novelist A.B. Yehoshua dismissed non-Israeli Jewish identity at a highly publicized panel in Washington. "Those who do not live in Israel and do not participate in the daily decisions that are made there and that are entirely Jewish," he told the audience at a centenary celebration of the American Jewish Committee, "do not have a Jewish identity of any significance. . ..You are just playing at Jewishness."

Although the notion that Jewish life in a Jewish state is fuller and more meaningful than diaspora Jewishness is an old Zionist leitmotif, its resurfacing in this form infuriated American Jewish leaders. Many who attended the speech resented the spectacle of an Israeli author slighting one of the most fertile diasporas in the history of Judaism and alienating Israel's strongest friends.

In Mr. Yehoshua and the Israeli Chief Rabbinate--the secular left and the religious right--we have two fundamentalisms, both schooling American Jews in the most elemental questions of Jewish identity, and both looking to Israel as the last and best word on Jewishness itself.

Together, the episodes reveal an Israel-diaspora relationship increasingly divided. Israelis are strikingly ignorant of American Jewish life: Students here do not learn about the diaspora; or if they do, it is as history, not contemporary reality. American Jews, meanwhile, continue to think of a devotion to Israel as an important part of Jewish identity, but have been largely ignorant of Israeli disregard for them. They won't remain in the dark much longer.

Mr. Balint has written on Jewish and Israeli affairs for Commentary, The Weekly Standard and the Forward. This article is online at http://www.opinionjournal.com/taste/?id=110008495