American Jews have feared this kind of attack for years, but still kept their doors open - here's why

People hold candles outside Pittsburgh’s Tree of Life Synagogue. Brendan Smalowski, AFP, Getty via CNN.

Like many American Jews, Rabbi Ethan Linden was in a synagogue on Saturday morning, reading a portion of the Torah, when a friend came and interrupted him.

Linden walked out of the synagogue and found a quiet place.

"And I did what I never do -- I made a call on Shabbat," he said, using the Hebrew word for the Sabbath honored by observant Jews.

Linden called his parents, who belong to one of three congregations that meet at Tree of Life Synagogue in Pittsburgh. Linden himself is a native son of Squirrel Hill, a friendly neighborhood with a vibrant and historic Jewish community.

Linden, a Conservative rabbi who now runs a Jewish youth camp in the Berkshires, said he learned Hebrew in Tree of Life's classrooms, played "eraser hockey" on its polished floors and celebrated his entry into adulthood, his bar mitzvah, in its sanctuary.

On Saturday, the rabbi, now 41, was relieved to hear his parents were safe, but grew horrified as it became clear that his childhood spiritual home had become a sickening crime scene.

Police say Robert Bowers, who repeatedly expressed anti-Semitic sentiments online, killed 11 people at the Tree of Life Synagogue. According to the Anti-Defamation League, it was likely the deadliest attack on Jews in American history.

The terrible death toll and shocking anti-Semitism drew lamentations from Jews around the world, from Israeli Prime Minister Benyamin Netanyahu to Rabbi Jonathan Sacks, the former chief rabbi of London.

"The deadly attack inside a synagogue earlier today in Pittsburgh, Pennsylvania has pierced the heart of Jewish communities worldwide," Sacks tweeted on Saturday. "The fact this attack happened inside a synagogue, whose name is the Tree of Life, makes it all the more horrific."

As they mourn their dead, Jews in the United States and elsewhere are also having difficult discussions about the tensions between the core Jewish value of helping strangers in need -- a tenet heartbreakingly taught in Saturday's Torah readings -- and the need to keep their communities safe from anti-Semites and others with violent intentions.

"I lived in Europe for two years," Linden said, "where synagogues are routinely guarded by gates and police officers, and sometimes require a passport to enter."

"Europe's history is why they have those guards," the rabbi continued, alluding to the Hitler-led Holocaust that killed 6 million Jews. "I am concerned that America's present will force us into that position as well."

American Jewish groups, including the Anti-Defamation League, have been warning for years about rising anti-Semitism in the United States. In 2017, there was a 57% spike in hate crimes against Jews, according to the ADL, the largest annual increase on record.

After the spate of bomb threats against dozens of Jewish Community Centers nationwide last year, Jewish groups sought and received increased federal funding for safety measures.

But the country's contentious political climate, inflamed by the midterm elections, has continued to feed anti-Jewish bigotry, according to the ADL. A recent ADL report on anti-Semitism and the midterms warned that "the Jewish socio-religious population in the US is being disproportionately targeted with disinformation and abuse during this crucial political moment."

"A staggering expansion of online harassment coincided with, and arguably fomented, the increase in offline anti-Semitism," the report continued.

Bowers stands accused of both, according to law enforcement officials.

Hours before opening fire in a Pittsburgh synagogue, he posted on the social network Gab that HIAS, a Jewish refugee resettlement agency, "likes to bring invaders in that kill our people. I can't sit by and watch my people get slaughtered. Screw your optics, I'm going in."

It wasn't the first time Bowers had used social media to attack HIAS, an organization founded in 1881 as the Hebrew Immigrant Aid Society, when American Jews welcomed Russian refugees with food and comfort on the docks of New York City.

After Jews became relatively settled in the United States and Israel became a haven for Jewish refugees, the organization turned its sights to others in need, partnering with the US government as one of nine national refugee resettlement agencies. Today, they help immigrants and refugees from South America to Syria.

"We thought we could take our empathy, our biblical texts and our religion's emphasis on refugees and use them to help others who, like our parents and grandparents, were seeking safety and a better life," said Melanie Nezer, HIAS' Senior Vice President for Public Affairs.

Weeks earlier, Bowers had criticized HIAS' "National Refugee Shabbat," an event marked on October 19 and 20 by some 300 synagogues and Jewish centers in North America, according to HIAS.

In New York City, a multifaith group that weekend talked about the importance of collaborating across religious and denominational lines. In Los Angeles, three synagogues came together for a service that featured music from a Syrian Jewish musician and dinner provided by a Syrian refugee family. In Kansas, synagogue leaders encouraged the gathering there to support political candidates "who share our values of welcoming the stranger and treating everyone with fairness and compassion." Some clergy drew connections between the global refugee crisis and the biblical story of Abraham leaving home in search of a new land, according to HIAS.

It seemed so uncontroversial -- so Jewish and so American -- to espouse these ideas, said Nezer. HIAS never imagined it could become fodder for anti-Semites.

"Local faith communities getting together to talk about their lives and traditions and how to help make other people's lives better. That's what 'Refugee Shabbat' was all about," Nezer said, her voice heavy with emotion.

The group has received hostile comments online before, but few overt threats. In the coming days, HIAS staffers will meet to discuss security and other safety issues, Nezer said, as will other American Jews.

On Sunday, Rabbi Linden made the long drive back to his hometown of Pittsburgh, where he plans to take part in a vigil at Soldiers & Sailors Memorial Hall. As he drove, the rabbi reflected on the Torah readings from Saturday.

It's a complex set of stories about Abraham and the founding of the Jewish people. Abraham welcomes strangers into his tent who bring very good news. The strangers tell the Hebrew patriarch that his wife, Sarah, who was aged and feared infertile, would bear a long-awaited child. The strangers, it turned out, were angels in disguise.

"It's one of the core stories that we tell ourselves about who we are as a people," Linden said.

But the biblical story doesn't end there, Linden notes.

In one of Scripture's most challenging passages, God asks Abraham to prove his loyalty by sacrificing his new son Isaac on a mountaintop. As Linden interprets it, the story is a warning against zealotry, religious or otherwise. In the end, God stops Abraham before he kills his beloved son.

"The way I am understanding the story today is that violence against an innocent person is never justified," Linden said.

"You might think you know what God wants and even what he has commanded, but in the end, the shedding of innocent blood is never what God desires."

By Daniel Burke, CNN Religion Editor. The-CNN-Wire™ & © 2018 Cable News Network, Inc., a Time Warner Company. All rights reserved.

The Gayly – October 29, 2018 @ 7:20 a.m. CDT.