PITTSBURGH — It was supposed to be Nancy Merenstein’s first day back at synagogue after staying home to take care of her disabled husband for weeks. For the longtime resident of Squirrel Hill — the hub of Pittsburgh’s dynamic Jewish community — Tree of Life synagogue has become a second home, one that reflected the neighborhood’s communal spirit.

But she decided to stay with her husband for one more Saturday, even though it meant missing the weekly lunch — challah, cheese, salads, tuna fish, dessert — shared by the synagogue’s two main communities, Dor Hadash and Tree of Life. It was a fateful decision.

The synagogue would become the scene of the deadliest attack on Jews in U.S. history. Eleven were killed — including Merenstein’s fellow Dor Hadash congregant Jerry Rabinowitz.

Physician Keith Murray and trauma surgeon Brian Zuckerbraun talk about the shooting at Tree of Life, a synagogue in Pittsburgh. (Drea Cornejo, Zoeann Murphy/The Washington Post)

“My 24-year-old grandson was saying that this is the first example of his life in anti-Semitism. It’s shocking to him. But not to me,” said Merenstein, 80. “The times we live in now make me think about Nazi Germany and how Nazism arose among people. It scares me.”

The deadly attack Saturday shattered the sense of peace and safety in Squirrel Hill. But the response has been true to the local spirit — politically spirited and resilient.

The aftershocks have unsettled others throughout the nation. Generations removed from the horrors of the Holocaust, American Jews are now forced to deal with the kind of brutality that originally drove many of their families to the United States.

Lingering on the edges of the tragedy are age-old questions that drill into the core of Jewish identity and play into existing religious and cultural divides: How to balance security and accessibility? Should Jews be an outward-facing community — or more inward-looking? These debates have characterized Jewish religious life since the Holocaust and been inflamed by recent attacks on Jews in Paris and Brussels.

The questions have become unavoidable — and urgent — here as Squirrel Hill works to absorb the recent violence.

Asked to describe the Squirrel Hill Jewish community in one word, Judy Grumet, a professor of psychology at the University of Pittsburgh, said: “Heimisha.”

The Yiddish colloquialism — meaning friendly and folksy — was used by several others to describe a community that was first settled by Eastern European Jews 90 years ago and whose brown-brick homes and leafy streets now represent the heart of Pittsburgh’s Jewish life.

“This is a place where everyone knows everyone, where if you need a favor you can just drop by and ask,” Grumet said.

Squirrel Hill and surrounding neighborhoods are home to almost 60 percent of the city’s 50,000 Jewish residents, according to a 2017 Brandeis University study. They have long felt at ease expressing their faith.

Every Friday, dining rooms glimmer with the light of Sabbath candles. Every fall, front lawns are lined with ritual tents to celebrate the week long holiday of Sukkot. Kosher cuisine is such an established part of the scene here that a beloved local restuarant — Milky Way — has an iPhone app to cater to demand for kosher pies and calzones from Jews and non-Jews alike.

Above all, Squirrel Hill Jews are recognized for their inclusiveness. Residents are not split by the denominational divides that typify other Jewish communities. The neighborhood mikvah — ritual bath — is open to all Jews, rather than those of the Orthodox persuasion alone. Jewish congregations of different religious outlooks also share buildings and are intimately involved in the others’ communal life.

“Jews here are far more interested in including you than they are asking questions that divide us up,” said Wendy Kobee, a 55-year-old Dor Hadash member.

Few places embody this community spirit more than the Tree of Life complex.

The main congregation is a relatively mainstream conservative Jewish community. Dor Hadash, a smaller group of professionals and academics, is geared toward social justice, with regular programming on topics such as the environment and prison reform. New Light is an older congregation established a century ago by Romanian Jewish refugees.

“All three of them are relatively small synagogues,” said Emily Rook-Koepsel, a Dor Hadash member. “Most of our [Dor Hadash] services are lay-led, so you have people helping set up folding chairs and stuff. Tree of Life has a rabbi, and there you have people coming in and meeting with each other. New Life is a lot of elderly people, so you have people helping each other downstairs.”

Their sacred space was still off-limits Sunday afternoon, wrapped in police tape and surrounded by camera crews. They had become refugees in their own city.

So members of the Dor Hadash congregation gathered at East Liberty Presbyterian Church, a little over a mile away, to comfort each other in privacy.

Fifty were expected, but 200 arrived on Sunday, ducking out of the falling rain into the church’s social hall.

“More and more people kept showing up,” Stan Angrist, 85, recalled. “And many of them were not members of Dor Hadash. But we were happy to have them.”

Hummus and pita, crudités and cookies were laid out for anyone with an appetite. They read poems and uttered prayers, shared stories about the dead and updates on hospitalized survivors. Tears rippled through the crowd. They reached for a popular Hebrew saying — “Am Yisrael Chai” — in defiance. The phrase means “the people of Israel live” and has been a rallying cry for Jews in the face of anti-Semitism for centuries.

Ultimately, this inclusive and socially progressive group of American Jews was forced to wrestle with what would come next.

“Do we stop everything or do we continue life?” said Wendy Kobee, a 55-year-old Dor Hadash member. “We continue living. This will not define us.”

The impact of violence at Tree of Life quickly ricocheted throughout the tight community. On Saturday, people who were not at the synagogue ran to other congregations to warn them. Others rushed across the street to tell their neighbors to stay inside.

Pia Naiditch, a 28-year-old interior designer and mother of three, watched in horror on Saturday as police cars raced through the streets. She feared they would turn down the route that, just a few minutes before, her husband and son had taken as they made their way to synagogue.

Naiditch’s family was unharmed, but the jolt of fear reawakened an old unease.

She had always worried something like this would happen. Jews — even in America — never feel entirely secure, Naiditch explained. History has been too unkind to them for them to ever feel entirely settled.

“When I go to synagogue, I am on guard, watching the doors,” she said. “I’ve always been like this. I don’t tell people, because I sound crazy. But I’m really not crazy, because these things happen.”

Rook-Koepsel said she had picked up a distinct rise in anti-Semitism before Saturday’s attack — a shift she ties to the acrimonious edge of current American politics.

“It’s certainly more prominent than it has been in many years,” she said. “I think many people have been given permission by leadership to be more hateful than they would have previously. And I think that has led to violence. This is not the first time, and it won’t be the last time.”

Squirrel Hill residents talk about their neighborhood in the wake of the fatal shooting at a Pittsburgh synagogue on Oct. 27. (Elyse Samuels, Zoeann Murphy/The Washington Post)

As American Jews now struggle to find a safe way forward, the search for security threatens many of the very open-arms values that defined Squirrel Hill.

“I think that security is going to become a big discussion in the Jewish community for sure,” said Rabbi Yossi Rosenblum, director of the Yeshiva Schools of Pittsburgh. “We don’t want all the doors locked, we want the doors open. . . . We want people to be welcome to come in.”

For Rook-Koepsel, the shooting should not push Jews from their path of social consciousness.

“It’s a very important part of a synagogue to think about the world and the best changes we can make in the world,” she said. “The last couple of hours, we’ve been thinking the best way to honor those that were lost is by voting and talking to people about making the world better.”