Jim Gaffigan isn’t Jewish. He’s Catholic. In fact, the New York-based comedian and actor was in the District on Tuesday to talk about his new book on being the Irish Catholic dad of a big Catholic family.

So how did he end up in front of a packed synagogue speaking bad Hebrew? “I think I just ordered the whitefish,” he said after a few fumbled words of greeting to the audience at the Sixth & I Historic Synagogue.

“They often start that way, with some reference to this space,” whispered Sixth & I Executive Director Esther Foer, standing at the back of the soaring 800-seat sanctuary packed to the balconies with laughing young urbanites, Jews and non-Jews alike. “It’s always so striking, the powerful effect it has.”

By “they,” Foer means the rapidly expanding roster of authors, filmmakers, artists, musicians and politicians that has transformed one of Washington’s oldest synagogues into one its hippest venues. Sixth & I, which was on the verge of being turned into a nightclub until sports mogul Abe Pollin and two other Jewish benefactors intervened a decade ago, has since emerged as a downtown cultural hot spot. Along the lines of New York City’s 92nd Street Y, Sixth & I is thriving as a combination lecture hall, performance space and religious institution at the center of the District’s youth explosion.

“I think we filled a hole that nobody knew existed,” Foer said.

Tina Fey picked Sixth & I for her only D.C. stop on a 2011 book tour. Adele played there in her pre-Grammy days. Mayor Vincent Gray gave his two most recent State of the District addresses from the bimah, the raised platform where the Torah is read. This month, you can buy tickets to hear Afro-Latin jazz, comedian Marc Maron, memoirist Jeannette Walls or journalist Gwen Ifill leading an author panel on the future of cities.

“They really seem to have found the right balance of commercial mass market and quirky programming,” said Anne Corbett, the former longtime director of CulturalDC, an arts advocacy group. “It’s not the Black Cat, but it’s not the Kennedy Center. It’s something in between.”

In the nine years since the century-old edifice was repurposed into a nonprofit arts venue with a $2 million budget and a killer sound system, it has elbowed its way onto the radar of publicists around the country.

“Sixth & I has gotten a great reputation in the last few years,” said Sally Marvin, vice president and director of publicity at Random House, which has booked author Salman Rushdie, photographer Annie Leibovitz, actress Ashley Judd and others at the synagogue. “We’re publicists, we talk among ourselves.”

Performers speak, riff, sing and dance — and sometimes swear, rage, grind and ridicule — on the railed altar, directly in front of the wooden ark that houses the synagogue’s sacred Torah. When the synagogue launched an ever-widening range of arts and entertainment programming — much of it secular, some of it edgy — its staff sought guidance from an Orthodox rabbi.

“He said as long as the ark is closed, it’s fine,” said Shelton Zuckerman, chairman of the Sixth & I board.

Zuckerman was one of three Washington real estate developers who stepped in to save the historic synagogue when it was facing a much more radical transformation. The Moorish-domed temple, built in 1908, was the home of Adas Israel until that congregation moved to Connecticut Avenue in 1951. Turner Memorial AME Church occupied the space for the next 50 years, before it made its own shift to the suburbs in 2002.

That’s when Zuckerman, who has built offices, apartments and shopping centers around the region, got a panicked appeal from the Jewish Historical Society of Greater Washington: Unless someone else bought it, the building was going to be sold for a nightclub.

He called Polin, the late owner of the Washington Wizards and developer of the Verizon Center just a block from the synagogue. It would cost $5 million, Zuckerman told him. Polin said to stand by.

“He called back in 10 minutes and said he would take a third and so would [Washington developer] Doug Jemal,” Zuckerman said.

Buying an empty synagogue was easy. Deciding what to do with it was harder. The three knew they wanted to preserve the Jewish heritage of the place, and they wanted it to be open to all Jews regardless of whether they consider themelves Reform, Conservative or Orthodox. But the three real estate professionals had to wonder: Would worshippers return to a neighborhood that had lost its Jewish population?

“The location demanded that we go for the 20s and 30s,” Zuckerman said. “We’ve seen a sea change [in demographics] downtown.”

After a $2 million renovation, Sixth & I launched services with a millennial bent, including sabbath services that begin with a happy hour or yoga. At a recent service for Shavuot, a holiday celebrating the Torah, “How I Met Your Mother” star Josh Radnor came to talk about how Jewish identity influenced his career and a local bartender served Shavuotinis in the basement afterward.

The synagogue, which doesn’t charge membership fees, draws a crowd of 200 to 400 worshipers for several services a week. Rabbi Shira Stutman, 39, was recently named one of the country’s 36 most-inspiring rabbis by the Jewish Daily Forward; Newsweek picked Sixth & I as one of the country’s 25 most vibrant Jewish congregations.

Foer is hearing from synagogues across the country that are eager to learn Sixth & I’s secret for drawing young folks and for selling out services for the Jewish High Holidays.

“We had a group from South Africa here yesterday,” Foer said. “Nobody expected that we would be bringing as many Jews back to downtown Washington as were here 50 years ago.”

She was standing by a backstage wall nearly black with celebrity graffiti. Among the notable speakers who have scribbled their names: former U.N. secretary-general Kofi Annan, author Nick Hornby and five Supreme Court justices. Broadcast journalist Mika Brzezinski left a lip print.

Building the arts programming was trickier, according to Jackie Leventhal, one of the staff of 16 responsible for booking speakers.

At first, Leventhal had to
wheedle publicists who had never heard of the venue. Now, they call her. In one recent week, she heard from reps for authors Malcolm Gladwell, Nicholas Sparks and Elizabeth Gilbert.

“Tina Fey was the game changer for Sixth & I,” said Leventhal, whose cubicle is crowded with green-room souvenirs labeled with Post-it notes: Joan Rivers’s wine glass, Justice Sandra Day O’Connor’s water bottle. “Now our biggest problem is scheduling; we don’t have enough nights in the week to fit everything.”

Tickets are usually $20 to $30, but can reach $45 for top draws such as Rivers and actress Diane Keaton.

Easing a litany of secular achievers into a religious space has taken adjustments on both sides. The staff recently cringed when an opening act exposed a little bit more of her person than is usual in temple. Speakers sometimes wonder how far they can go. When author Terry McMillan was really getting into a juicy anecdote at her April appearance, she stopped suddenly and looked at Leventhal in the front row.

“Am I allowed to curse in here?” she asked.

“I gave her the thumbs up,” Leventhal said.

Foer recalled a moment when she realized that the arts and spiritual programming had begun crowding each other. They had inadvertently booked a comedian on Tisha B’Av, a holiday of profound mourning on the Jewish calendar. She called the rabbis.

“One them sat with me and said, ‘On the one hand, it’s a little embarrassing,’ ” Foer remembered. “‘On the other, you have a contract.’”

He advised them to carry on with the event, she said, “if we didn’t publicize it.”