These Millennials Got New Roommates. They’re Nuns. A project called Nuns and Nones moved religion-free millennials into a convent.

BURLINGAME, Calif. — Sarah Jane Bradley was an unmarried, “spiritual but not religious” professional in her early 30s, with a rowdy group of friends and a start-up when she moved out of her communal house and into a convent.

A bunch of friends went with her.

They called the project Nuns and Nones, and they were the “nones” — progressive millennials, none of whom were practicing Catholics. Intended to be a pilot project, the unusual roommate situation with the Sisters of Mercy would last for six months.

The idea was spearheaded by Adam Horowitz, a 32-year-old Jewish man, and the pilot program was guided by Judy Carle, a 79-year-old Catholic Sister of Mercy in the Bay Area. Mr. Horowitz and his friends heard the call after a road trip to visit intentional communities. They were brainstorming ways they could live radical activist lives, lives of total devotion to their causes. They were trying to figure out who was already doing this, and when Mr. Horowitz talked to a minister, it came to him. The answer was nuns.

“These are radical, badass women who have lived lives devoted to social justice,” said Ms. Bradley. “And we can learn from them.”

These are also hard times for the sisters. The average age of a Roman Catholic nun in the United States is close to 80. Convents around the country are closing. The number of nuns in the United States has collapsed from 180,000 in 1965 to below 50,000 today. Sisters are passing leadership at Catholic hospitals and schools to lay people. Some have even begun talking about their mission here in America as being complete.

At the same time, millennials are the least religious group of people in America — only about 27 percent attend weekly religious services. Young women who aspire to lives of good works without the burden of a husband are quite able to do that now without Catholicism.

Yet for small pockets of the young, urban and progressive, the convent is calling. Their radical politics took them all the way around and back to the Catholic Church.

The Millennials Arrive

The millennials arrived by Subaru. The sisters had prepared small rooms for the women and men alike, in the wing where they originally housed novices but now use for retreats. Each room had a twin bed, a small wooden desk, a chair and a Bible. The sisters also made them an office with specifically chosen sacred art, including a painting of Moses because some of the Nones were Jewish.

The sisters were not sure what exactly the young people wanted to know about them, and the first meeting came as a shock.

“I was stunned, and I said to the other sisters, ‘You will never guess what the millennials want to talk about: the vows,’” said Sister Patsy Harney. “Everybody laughed. It was kind of like a joke, you know?”

But the millennials were nothing if not earnest.

Sister Harney found a book on the vows — poverty, obedience, chastity — that she had bought once but never read.

“I saw Alan creeping around with his cellphone to take a picture of the cover, and then next time I saw it Sarah had been reading it and it was full of Post-it notes all over,” Sister Harney said. “Millennials were looking at it like this is the glue. They were looking for the secret sauce of how we do this.”

The sisters began to see that the millennials wanted a road map for life and ritual, rather than a belief system. On one of the first nights, Sister Judy Carle said, one of the young people casually asked the sisters, “So, what’s your spiritual practice?”

“That’s the first question, not, ‘What do you believe?’” she said, noting that throughout history, the specifics of belief were so important that people fought wars about it.

“So many of the millennials would say, ‘I’m looking for rituals. I’m looking for rituals to work in my lesbian community or social justice or I need rituals for this other thing,” Sister Carle said. One young woman wanted ritual so much that she started going to Mass every morning.

The millennials worked their normal jobs during the day, but in the evenings and on weekends the group had a slew of activities. They joined for convent feasts and Easter vigil. They had their feet washed on Holy Thursday. They studied the prophets. They invited the sisters over for Shabbat dinner.

One night, a group of millennials and sisters were dancing and laughing. They got so loud that a security officer came and knocked on the door and told them the party would have to continue in the basement. It did.

Sister Janet Rozzano, 81, chose not to be involved with the young visitors at first, but they started using her kitchen.

“I kind of got thrown into it,” she said. “We just had so much in common to talk about.”

Sister Rozzano spends most of her time coaching her fellow sisters on their own journeys. Much of this now involves the challenges of living in an aging body.

“One of the challenges of aging is not just to focus down on your aches and pains,” she said. “And I feel like this called me back again to the bigger vision. And on a simple level I overcame my fear of talking to younger people.”

In the end, she wrote a haiku about the millennials.

Eek. What will I say?

I’m too old for millennials.

Surprise, we’re soul mates!

For the Sisters

Nuns and Nones is now running groups in about a dozen cities, including Grand Rapids, Mich., Minneapolis, New York City and Boston. In each locale, groups of sisters and millennials meet regularly. (The sisters are colloquially known as nuns, though technically that term only refers to the cloistered women who do not engage in work at outside schools or hospitals.) The just-concluded pilot residency in California is the first attempt at cohabitation.

Wayne Muller, a minister in Santa Fe, N.M., was the one who originally suggested to Adam Horowitz that a partnership between millennial activists and sisters might be worth exploring. He has been surprised at how well the activists have taken to the program and how quickly they have begun to see the sisters as comrades.

“It’s like, ‘There’s a pope you know; they’re in his Rolodex, and it’s always a him — and you guys are O.K. with this?’” Mr. Muller said in an interview.

That these young progressives — working as community organizers, artists and social workers — are finding answers in the Catholic Church is a surprise to them, as well. Many of the young people say they view convent culture as an almost separate, rebel force, hardly related to the Catholic Church at all — though of course it is an integral part of the church.

And that church has hardly seemed like a place for young progressives. In recent years, the church has been in a prolonged crisis around sexual abuse and systematic cover-ups.

To Mr. Muller, Nuns and Nones is also, in part, a real estate story. Moving young people into convents can help sisters hold onto their property amid rising nursing home care costs. The young people get low-income housing in exchange for helping take care of the sisters. (The young participants bristle at the suggestion that their interest has to do with housing costs; they worry about being seen as gentrifiers of convents.)

Mr. Muller said another benefit for young activists is to learn to avoid burnout by studying the sisters, who have made social change a lifestyle.

“The call itself is very similar,” Mr. Muller said. “The sisters have been doing radical social justice work for forever.”

Many of the Nones are looking at Catholicism anew, even as they rarely use the word, speaking about it more loosely in the new language of spirituality.

“A lot of us in social justice, a lot of the people of our generation, it’s this culture that’s all about forward-moving progress, and that forgets that there’s this cyclical spiral and these really old wisdom traditions that can feed change,” said Christina Tran, a 34-year-old comic artist in Corvallis, Ore., who organizes monthly Nuns and Nones meetings. “It’s less about building anew; it’s more about remembering.”

What happens when those “really old wisdom traditions” include opposing gay marriage and abortion rights?

Mr. Horowitz was loath to answer, finally settling on: “We engage in dialogue about that.”

Chastity, Poverty, Obedience

The Nones, many of whom said they felt overwhelmed by life’s choices, were drawn to the discipline and the notion of sacrifice. A life of chastity was especially appealing to them.

“I started to realize chastity was an invitation to ‘right relationship’ and not just about celibacy,” Sarah Jane Bradley said. “In an era of Me Too, we need right relationships. We need to know what it means to respect someone’s personhood and to respect your own personhood and to be a conduit for love rather than ego needs.”

Ms. Bradley is the co-founder of an adult learning support community called Open Master’s, which includes a program for those interested in religion called Alt*Div. She is not planning on a life of celibacy, but she does want a little infusion of chastity.

“It’s about deciding what’s the price we’re willing to pay for the world that we want to live in and the life we want to live,” Ms. Bradley said.

David Bronstein, a 31-year-old academic tutor and education activist who lived in the convent during the program, agreed. “Chaste also means devoted to a way of life,” he said.

For Mr. Bronstein, who will be leading a “food justice learning journey” for high schoolers this summer, it has meant saying “no” to more things and keeping his calendar emptier.

“Chastity has been about taming the work beast and reorienting from that and toward a primary orientation toward spirit and community,” Mr. Bronstein said.

The millennials started rethinking other vows. The vow of poverty is about stewardship of resources and shared prosperity, they said. But obedience, as a concept, was tricky.

“It sounds like it’s about taking orders, but the sisters helped me see it’s about preparing the heart for dialogue and a deep internal listening for truth,” Ms. Bradley said. “The vows opened up this portal in which to really appreciate how countercultural the lives these sisters have led are.”

It’s hard to adopt practices that stem from vows without belief — hard to do a Cliff’s Notes version of 60 years in a convent.

For example, the millennials became interested in the idea of discernment, a process the sisters use to sift and orient options to more closely listen for God’s call.

“But now I’ve heard millennials saying they need to ‘discern what I’m up to this afternoon,’” Mr. Horowitz said. “And it’s so important we don’t dilute it.”

The sisters’ days are full. Many start prayer at 6:30 a.m. in the chapel and then work on the large hospital network their order founded or their affordable housing program, which serves 152,000 people nationally. The millennials kept more flexible hours.

“I was envious,” Sister Carle said to the millennials one morning. “Our lives are going on and sometimes faster. Yours was more like what I would call a retreat-type experience.”

Passing On Mercy

Other convents heard about what was going on and started to get interested. People in Rome started asking about it, and the president of the Leadership Conference of Women Religious mentioned Nuns and Nones in a recent address.

“They want to know how we found them and if there are more like them,” Sister Harney said.

Many of the Sisters of Mercy had joined the order en masse with friends after Catholic high school. As teenagers, they saw how much fun their teachers seemed to be having. The church seemed like a more adventurous and idealistic life than traditional marriage.

“I saw the sisters as women who were living their lives for the more,” Sister Carle said.

Through the church, these women could take enormously powerful roles heading hospitals, housing projects and schools.

“We’ve had opportunities and pathways for leadership that other Catholic women didn’t have — that other women didn’t have,” Sister Carle said.

For decades now though, the story of sisters has been one of diminishment.

As they have been passing their leadership roles at those hospitals and housing projects on to lay people, they have found that often men replace them. And what worries them most is who will inherit their charism — the great spiritual gift their order brings. For the Sisters of Mercy, that gift is, naturally, mercy.

Soli Salgado, a reporter for Global Sisters Report who has been tracking the Nuns and Nones movement, said she thinks this is the sisters’ most existential worry.

“When they talk about dying out, they’re less concerned about making sure the institution survives and more about who’s going to inherit the charism, who’s going to keep doing this mission that’s been fueling them all these centuries,” Ms. Salgado said. “For the sisters, Nones and Nuns could be a vehicle for passing along their charism.”

A Farewell, for Now

The night the Bay Area residency came to end, the sisters and millennials gathered in a circle around a small altar. Sisters and millennials wrote and read poems to each other. And they sang one of the sisters’ chants: Sacred is the Call. Awesome indeed the entrustment. Tending the Holy, tending the Holy.

When the millennials moved out in mid-May, they scattered back around the country. The Sisters of Mercy, of course, remain at the convent.

Some of the sisters are now answering a call to go to the U.S.-Mexico border for an extended stay. They plan to work with asylum seekers. The Nones could come too, if they are up for it.