Six of the most prominent religious figures in American Jewry went before the microphones at a news conference in New York yesterday to emphasize the necessity of a "high-level and independent" investigation into the massacre of Palestinians in Beirut.

"It is now common knowledge that the recent Beirut massacres were perpetrated by Christian militias," their statement said. "Nevertheless, the obligation that the Israeli government assumed when Israeli troops took over West Beirut and their proximity to these events make it urgent that every step be taken by all appropriate parties . . . to determine how this tragedy occurred."

The rabbis' statement reflected the bewilderment and confusion that has swept across the large and diverse American Jewish community in recent weeks. This has led to an unusual and clearly painful public questioning of both the actions of the Begin government in Israel and the widespread condemnation of his government, deflecting on Jews throughout the world.

There has been self-searching and doubt, anger and frustration, anxiety and fear, some of it expressed in public statements and the media, some behind closed doors.

There remains an absolute bedrock commitment to the "safety and security" of Israel, but what constitutes that security is being called into question.

It is here that the usually solid consensus of organized American Jewry is beginning to show cracks, a phenomenon the Reagan administration clearly recognized in assessing the American political response to his recent Middle East peace initiative.

"We are taught that he who destroys one life, it is as if he destroyed the entire world," Rabbi Norman Lamm, an Orthodox rabbi who heads Yeshiva University, said yesterday in conjunction with the statement in New York, adding that the worldwide moral outrage over the Beirut deaths has been fitting.

" . . . Yet, there is perhaps an overreaction, not to the massacre, but to the whole picture. There is no excuse for the one-sided barrage of criticism against Israel, a rhetorical pogrom, a journalistic mugging. We must urge impartial attitudes rather than selective criticisms."

Reflecting a sentiment often heard now in the Jewish community, the rabbis asked that, along with the probe into the Beirut massacre, "a parallel inquiry be undertaken by appropriate bodies as to how it was possible for tens of thousands of Christian and Moslem civilians, both Lebanese and Palestinians, to be obliterated since 1975 under PLO and Syrian domination in Lebanon. Here, too, responsibility must be fixed."

Joining with Lamm were such prestigious and powerful members of the Jewish community as Rabbi Gerson D. Cohen, chancellor of the Jewish Theological Seminary; Rabbi Joseph B. Glazer, executive vice president of the Central Conference of American Rabbis; Rabbi Paul Martin Steinberg, dean of the Hebrew Union College; Rabbi March Tanebaum, a director of the American Jewish Committee, and Rabbi Walter S. Wurzburger, president of the Synagogue Council of America and a refugee from Hitler Germany.

The theme of the Nazi Holocaust era was a recurring one in yesterday's statement and an undercurrent in almost every discussion with Jewish community leaders. It is a theme that has been the bond between American Jews and Israel and the cement that holds together the scores of organizations that often are taken to represent the American Jewish community.

Ever since President Reagan's Middle East peace initiative was launched three weeks ago, and particularly since the revelation last weekend of the Beirut massacre, that community has been riding an emotional roller coaster and speaking with anything but a single voice.

The Conference of Presidents of Major Jewish Organizations, the umbrella group that is supposed to speak for the organized Jewish community on matters involving Israel, has made no public statement on the question of investigating the massacre.

"On something like this, everyone would agree that there must be an investigation. There probably would be disagreement whether American Jewish organizations should speak out publicly, however," said Julius Berman, a New York attorney who is chairman of the conference. "Some organizations have cabled Begin but felt it does not help to issue a press release. Knowing the prime minister, he would say: 'You know how to speak to me; you don't have to speak through the New York Times.' "

Not all have been reticent, however, as demonstrated by the six rabbis yesterday and by politically active groups like the American Jewish Committee and the American Jewish Congress.

There also has been a proliferation of voices in response to the Reagan initiative, emphasizing that an Arab willingness to negotiate is a precondition to any successful resolution.

More than one prominent figure in the American Jewish community has found positive aspects to the Reagan proposal, in contrast to Begin's outright immediate rejection. It is on this issue that the differences over "safety and security" surface.

Hyman Bookbinder, long-time Washington representative of the American Jewish Committee, is one of those who has spoken positively of the Reagan proposal, which calls for a federation of the West Bank with Jordan to provide a home for Palestinians.

"Jews have concern about basic security, viability and continuity," Bookbinder said, "and in this context Israel is central to Jewish consciousness. There is a psychological equation between a threat to Israel and the Holocaust. Therefore rallying to Israel's defense doesn't take a phone call. It may even be more so because there is a troublesome prime minister. It is no different when there is a threat to Jews in Latin America, or Paris, or to 80,000 in Iran: there is an instinctive reaction.

"But what is a question of security? Egypt crosses the Suez Canal -- yes. Katyushas on the northern border -- yes. A PLO state -- yes. But giving up parts of the West Bank for something other than a PLO state -- Begin says yes, but maybe it is not a threat to security. Maybe it is more of a threat to have 1.5 million more Arabs.

"It is clear Begin's determination to keep control on the West Bank flows from his deep ideological commitment. Many in the community have said, 'We will support claims on part of the West Bank on security grounds, but now, in 1982, you can't do it on biblical grounds.' Now the prime minister has heard that and is stressing security first. It is possible to use the security argument casually or even deceitfully."

The two debates in the Jewish community -- taking a position on the Reagan initiative and calling publicly for a independent probe of the massacre -- now have combined with other phenomena to create an extraordinary sense of unease.

Israel is pilloried, many argue unfairly, throughout the world. It is the fund-raisers who sense it most acutely, those who meet with people who represent the broadest cross-section of American Jewry as they seek support for everything from Israel Bonds to old age homes.

"I have seen surprising turnouts and interest in recent weeks," said one Washington area field worker, who added that contributions have been on target. "People are worried and concerned and they are coming together."

A field worker from another part of the country put it differently, drawing an indirect analogy to the Weimar era, when the fragile security of the German Jewish community crumbled under the Hitler movement. "It is shattering to us that we no longer are the guys in the white hats -- all the support for the symphonies, the museums, the universities . . . . Nothing can be taken for granted any more," he said. "The secure role we thought we had can no longer be."

The emotions swirling around the debate have been even more intense because they have come during the Jewish high holy day season, a point the six rabbis noted in their statement yesterday that called for investigations of the Beirut massacre and the years of violence in Lebanon:

"This high holy day season which will be climaxed by the observance of Yom Kippur beginning this Sunday evening, attests powerfully to the Jewish conviction . . . that all mankind are equally members of God's human family, deserving of the right to life, dignity, compassion, and human solidarity."

One prominent Washington political activist, who has been at the center of the debate, paused for a moment yesterday as he considered the events of the past three weeks and then said: "There's going to be a lot of crying Sunday night."