In normal times, a rabbi delivering a benediction at an inauguration would be cause for Jewish communal pride. But these are not normal times. By accepting an invitation to offer a prayer at Donald Trump's inaugural ceremony, Rabbi Marvin Hier, founder of Los Angeles's Simon Wiesenthal Centre, provoked a furious response from Jewish liberals.

Critics note the irony of Rabbi Hier — whose organisation is named after a famous Nazi hunter and operates a “Museum of Tolerance” — blessing the inauguration of a president who excites neo-Nazis.

Indeed, Mr Trump’s angry rhetoric aimed at Muslims, Mexicans and international banks has energised America’s fringes, unleashing an unprecedented torrent of online abuse aimed at Jewish journalists and sparking a spree of swastika vandalism. Mr Trump has already inaugurated a new normal.

Still, we should not exaggerate the threat faced by American Jews. The white supremacists may be emboldened, but they remain a tiny and bitter fringe. By contrast, Jews are well integrated into American society, integrated even into Mr Trump’s own family and circle of supporters and advisers.

American Jews are well positioned to weather the storm that Mr Trump has unleashed. The same, however, cannot be said for the organised American Jewish community. The next four years will challenge its assumptions, its values, its strategies, indeed the very notion of a cohesive American Jewish community.

In every presidential election, American Jews can be counted upon to give the lion’s share of their votes to the Democratic nominee. But American Jewish organisations strive to maintain good relations with Democrats and Republicans alike, working with presidents of both parties.

This time business as usual — proffering customary congratulations to the president-elect, rabbis offering public blessings, inviting Mr Trump or his advisers to communal functions — is simply unacceptable to a significant portion of the three-quarters of American Jews who voted against the president-elect.

Yet the threat of a backlash has not deterred some groups. The main communal coordinating body on Israel, the Conference of Presidents of Major American Jewish Organisations, hosted a Chanukah party at Mr Trump’s new hotel in Washington, prompting several of its liberal member groups to skip the event in protest. The right-wing Zionist Organisation of America invited Mr Trump’s most controversial adviser, Steve Bannon, former chairman of the incendiary right-wing website Breitbart, to its gala dinner in New York. Mr Bannon did not show up, but hundreds of young Jewish protesters did.

Some establishment Jewish groups have spoken out strongly in response to Mr Trump’s more outré moves. The Anti-Defamation League’s leader, Jonathan Greenblatt, vowed to register as a Muslim if the Trump administration sets up a registry to track Muslims. The Union for Reform Judaism and the ADL both vocally opposed Mr Trump’s selection of Mr Bannon as his chief strategist. A slew of liberal groups objected to Mr Trump’s pick for ambassador to Israel, bankruptcy lawyer David Friedman, who derided Jewish supporters of the dovish Israel policy group J Street as “kapos”. Yet even these groups have picked their battles.

Others are more cautious. Those focused on building support for Israel are loath to alienate an incoming administration that is seen as friendly by the Israeli government. Those focused on providing social services are generally disinclined to pick fights.

But establishment groups — many of which in recent decades have become more distant from the grassroots, more responsive to wealthy donors, and more Israel-focused — face a challenge from an insurgent Jewish left uninterested in carrying water for the Israeli government.

Throngs of young Jews have taken to the streets against Mr Trump in demonstrations organised by IfNotNow, an activist outfit that had previously protested at established Jewish groups’ offices to advance its “demand for American Jewish institutions to end their support for the occupation”.

Young Jewish progressives, who see opposition to Mr Trump as a moral imperative, will accept no excuses from the establishment. Jewish groups that confronted President Barack Obama over Israel and the Iran deal will have a hard time justifying a cautious response to Mr Trump’s domestic agenda. (And an Israel that embraces Mr Trump risks further damaging its already declining standing among liberals.)

But the Jewish left is not the only insurgent force in American Jewish politics. Remember, nearly a quarter of American Jews voted for Mr Trump. While some prominent neoconservatives maintain their antipathy toward the president-elect, many other Jewish Republicans have fallen into line, and others were in line from the start.

The Jewish community is a house divided, with a liberal-leaning majority and an assertive conservative minority that includes many Orthodox Jews as well as leading communal donors.

The split over Mr Trump shows that the American Jewish divide has widened to the point of mutual incomprehension, mirroring fissures within American society at large.

In the era of President Trump, American Jewry’s divisions can no longer be papered over. Straddling the intra-communal divide will become increasingly difficult, as American Jews demand of the organizations that purport to represent them: Which side are you on?

Daniel Treiman is a former managing editor of the Jewish Telegraphic Agency and a former opinion editor of the Forward