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Most people think of Lag B'Omer (this year on Sunday, May 25) as a warm, fuzzy semiholiday with a nature-loving theme.

But in the Talmud, the 33rd day of the Counting of the Omer period is a devastating reminder of a catastrophe caused by Jews' divisiveness.

Today, Jewry seems headed for a repeat of the disaster.

In a short time, tens of thousands of Rabbi Akiva's students died because "they did not treat each other with respect," concludes the Talmud. Akiva and some of his students proclaimed Simon Bar Koziba, the leader of the Bar Kochba revolt in Judea against Rome, to be the Messiah. But colleagues opposed the revolt. Rabbi Yochanan Turta mocked Akiva.

If the students and rabbis had talked it over respectfully, perhaps they all would have devised a sober strategy of resisting the Romans. Using all the different approaches, they might have reached the masses, and could have overcome the enormous contempt that persisted between scholars and the unlearned people.

Instead, there was a revolt that brought a crushing defeat and 1,800 years in exile. Many Jews were killed.

Now we face a social catastrophe in the making.

The behavior of Orthodox, Conservative, Reconstruc-tionist and Reform leaders today echoes the Talmud: "They did not treat each other with respect."

That divisiveness has grown since the 1960s, amid a "plague" of American-Jewish assimilation.

Reform leaders responded to a growing constituency of intermarried couples by recognizing as Jewish children born to Jewish fathers and non-Jewish mothers — dismissing Orthodox objections. Conservative rabbis also rejected patrilineal descent.

In another sign of "lack of respect," Reform leaders concluded that Conservative laypeople had lower standards than their rabbis, that the laypeople would accept patrilineal Jews and that they would force the Conservative rabbinate to go along.

A plague of divorce swept the Jewish community.

Second marriages performed without benefit of a get, or religious divorce, threatened to create halachically unmarriageable children. Rabbi Moshe Feinstein ruled that Reform marriages were halachically invalid, thus requiring no get to end them. It was easier to rule that Reform was an invalid religion than to validate Reform marriages and thus require a higher level of interdenominational cooperation to assure that Reform laypeople would obtain a get.

Important Reform rabbis welcomed Feinstein's solution. They accepted disrespect so that they, in turn, wouldn't need to temper their behavior for the sake of the Orthodox.

The Reform movement has little or no respect for Orthodox positions on homosexuality and on intermarriage — calling them "homophobic" or "unrealistic."

Now the disrespect has boiled up further.

While the mainstream Orthodox leadership disowned the Union of Orthodox Rabbis' declaration that "Reform and Conservative are not Judaism at all, but another religion," they are also angry at liberal groups' rejection of tradition. Therefore, they did not make a statement unequivocally legitimizing liberal movements.

No centrist Orthodox leader seems able or willing to publicly respect Reform and Conservative Judaism by asserting their legitimacy.

Now the leadership of the liberal movements has dropped all restraint. Jewish Theological Seminary Chancellor Rabbi Ismar Schorsch recently called the Chief Rabbinate "dysfunctional" and said its religious courts are "without a scintilla of moral worth."

Schorsch called for a religious center "for whom piety and sanity are not polar opposites." The Conservative leader also called upon all Jews to "recommit ourselves to the goal of achieving" religious unity.

Rabbi Eric Yoffie, president of the Reform movement's Union of American Hebrew Congregations, described the Israeli rabbinate as "medieval," "extremist," "radical," "fanatic" and "a disgrace to the Jewish people."

Schorsch and Yoffie both know that they must deepen their constituents' spiritual life, education and observance levels. They know positive exposure and contact with the Orthodox community will upgrade liberal Jews in those areas in which Orthodoxy is strongest — learning, observance and community.

But by now, anger and lack of respect prevail.

Rabbi Norman Lamm, president of Yeshiva University, and Agudath Israel of America know that the Orthodox community is weakest in coping with new roles for women and in facing the challenge of social action. They know that Orthodoxy has a lot to learn from the liberal movements in many areas.

They know that insulation has kept intermarriage and assimilation rates among Orthodox low — so they will have to face these issues in time and, again, will have to learn from liberals.

But right now they cannot admit or even articulate such ideas.

Unless all Jews stand up for unity, we may be heading for a fundamental schism. Only spotlighting the forces of divisiveness, generating strong internal pressures within each movement to take other groups into account and increased support for active dialogue and joint activity can arrest this slide toward alienation and separation.

This Lag B'Omer, every Jew should pause a moment in silent tribute to the memory of Akiva's students who died untimely deaths. Then there should be a second moment of confession and repentance for the coming untimely death of Jewish unity.