If you don’t build it, they will come.

That’s the credo behind Shir Neshama, a six-year-old Jewish Renewal congregation in central Contra Costa County. The congregation has about 40 member families, a religious school, a rabbi and a Torah.

What it doesn’t have is a synagogue. And that’s just the way the congregants like it.

Instead, Shir Neshama congregants meet in chavurot (small groups), four in all, gathering in members’ homes for services with the rabbi traveling week to week with his own Torah and portable ark.

The rabbi is Sholom Groesberg, a spry 85-year-old who originated the idea of a shul without walls.

“I wanted to see if it was possible to have a Jewish congregation if money were taken out of the equation,” says the Walnut Creek rabbi. “Too often, money is an impediment to affiliation. The High Holy Days, the building fund, the bar mitzvah: It’s a lot of money. Half the Jewish population doesn’t affiliate. There’s got to be a reason, and a lot of it is financial.”

At Shir Neshama, the rabbi takes no salary and no one pays dues (though at times congregants pass the hat for special occasions and space rental for the High Holy Days). Interfaith couples are common, with many saying the inclusive nature of Shir Neshama makes the congregation special.

Magda Lopez, a Cuban-American attorney, grew up Catholic but never felt comfortable in the faith. Married to a Jewish man, she remembers when she and her husband were shul shopping. “It had to be one that felt good to me. I wanted to feel welcome and included, that it didn’t make any difference that I wasn’t Jewish.”

Today, Lopez is an active member of Chavurah Dalet, one of the four Shir Neshama chavurot. The others are nicknamed Aleph, Bet and Hei.

“In our chavurah, there’s always a subject of substance,” says Lopez of a typical Chavurah Dalet Shabbat. “We light the candles, we sing, we do prayers, we eat, then we have a program around the [Torah] portion.”

Over at Chavurah Hei, the emphasis is on social action. Says member Rob McKie, “We prepared food in our homes for the homeless and took it to shelters. The kids could participate, and we’d have dinner with the folks. We did that every Sunday for a year.”

Daryn Stier, a member of Chavurah Dalet, says her group teamed with Heifer International, an organization that helps Third World residents become self-sufficient. Her chavurah raised money to purchase a goat for an North African village.

Other chavurot specialize in music. Though small, Shir Neshama has given rise to two musical ensembles: one, the klezmer-oriented Shabbatones, led by the rabbi; the other, the a cappella trio Jew-Ops, of which Stier is a part. Both groups perform frequently at lifecycle events and Shabbat services.

Groesberg is in many ways the center of this far-flung congregation, whose members live everywhere from Martinez to Concord to Lafayette.

He came to the rabbinate late in life after many years as a professor of engineering, and later dean of an engineering college in Chester, Penn. “I wanted to do something else,” he remembers. “I tried to figure out what was important to me at that stage in life. My Jewishness was what was important.”

In 1984, the Brooklyn-born Groesberg was ordained at the Academy of Jewish Religion, a transdenominational seminary in New York. He filled a couple of posts in Texas synagogues before moving to the Bay Area to become rabbi at B’nai Torah in Antioch.

Though he technically retired in 1997, Groesberg wanted to continue serving. A fan of Berkeley’s Aquarian Minyan, he hoped to bring an egalitarian Renewal presence to Jews living on the east side of the Caldecott Tunnel. That sparked the birth of Shir Neshama.

“I admire Sholom’s attitude [about inclusivity],” says McKie, a non-Jew married to a Jewish woman. “He had this concept where the congregation would be very welcoming, and even cater to interfaith families.”

“My model presupposes that with time, a leadership emerges within the chavurah,” adds Groesberg. “Then I scale back accordingly. The more they direct things, the less they have need of me.”

His congregants might disagree.

“Sholom is our unifying force,” says Lopez. “He’s charismatic and intelligent. I don’t know if we can find another rabbi like him.”

Groesberg himself is aware that the march of time will trigger changes for Shir Neshama in the years ahead. “They might need to form a nonprofit, establish a treasury and think about hiring some sort of spiritual leader who will have to be paid,” he muses. “It smacks of institutionalization. That’s the thing the model tried to avoid.”

But such steps are not quite on the drawing board yet.

For now, the focus remains on building community and living Jewish lives. “I felt a sense of community and purposefulness here,” says Stier. “Having so much room for creation and creativity made it a place that felt like a home base for us.”

That translates into Shabbat joy every weekend in the homes of Shir Neshama congregants. And where they go, so goes their intrepid rabbi, always ready to rock.

“I’m a busy guy,” says Groesberg, “and happy to be so.”