A massacre in New Zealand on jumah, the Muslim weekly communal prayer.
Suicide bombings in Sri Lankan churches on Easter, the holiest day of the Christian calendar.
On Saturday, another attack inside a sanctuary, this one on the final day of Passover, a sacred time commemorating Jews' escape from violence and oppression in ancient Egypt.
Saturday's shooting at Congregation Chabad in Poway, California, came six months to the day after the worst anti-Semitic violence in American history, when an accused white supremacist slaughtered 11 Jews inside a Pittsburgh synagogue.
After Saturday's attack, Chabad, an Orthodox Jewish movement, addressed the recent spate of sacrilegious violence, of which it was the latest victim:
"The fact that these G-dless acts have multiplied of late underscores with even greater urgency the critical need for proper moral education for our youth, rooted in the belief in a Supreme Being -- Whose Eye that Sees and Ear that Hears should preclude anyone from devaluing the life of another human being."
But as American Jews and other faith communities confront the wave of violence and seek to sooth fearful congregations, some are calling for more than divine aid. They are also asking for law enforcement to step in and protect them, while trying to remain welcoming to outsiders. For some, the frustration is palpable.
"When will this open-hunting season on Jews end?" asked David Harris, CEO of the American Jewish Committee.
"Without in any way minimizing the incredibly dedicated efforts of officials to date, heightened action is required, or else we sadly could one day be reacting to yet another attack on a synagogue, or for that matter, on a church or a mosque, or another house of worship."
As the beginning of Ramadan approaches on May 9, many American Muslims say they fear the next attack is imminent, and this time it will target an American mosque.
"There isn't a mosque in America right now that hasn't had conversations about where they are going to get more resources for security," said Dalia Mogahed, director of research at the Institute for Social Policy and Understanding.
Some mosques have applied for government grants for security cameras and guards. Others are holding fundraisers, Mogahed said.
Theories vary on why houses of worship across the world seem to be under increasing threat, though attacks on sanctuaries remain relatively rare.
The attacks on Jews and Muslims in the United States were allegedly carried out by white supremacists. An extremist Islamist group has been blamed for the attacks in Sri Lanka.
Some say the attacks are a result of a rapidly changing world and the fearful response of those who would want to keep their country "pure" and religiously monolithic.
Others blame top leaders in the United States for failing to recognize the danger of a metastasizing movement of white supremacists.
'The biggest challenge in the world today'
After the mosque attacks in Christchurch, New Zealand, President Donald Trump was asked whether he saw a worrying rise in white supremacy movements around the world. Trump said he did not, blaming a small group of people "with very, very serious problems."
Trump also told reporters that he had not seen the manifesto linked to by a social media account believed to belong to the accused Christchurch attacker, which mentioned the president by name and portrayed him as a symbol of renewed white identity.
Diana Eck, who heads Harvard University's Pluralism Project, which studies issues that arise in multireligious societies, said spasms of violence are common during eras of rapid and widespread change.
"The biggest challenge in the world today is how to live with religious, cultural and racial differences in ways that go beyond a laissez-faire tolerance but actually build toward common goals."
In the United States, the religious landscape has dramatically shifted in the last several decades, Eck said, as Muslims, Hindus, Sikhs and other religious minorities have immigrated from overseas.
Many if not most Americans have welcomed the country's relatively new religious diversity. But some are alarmed by it, Eck said, and are willing to take innocent lives in the name of white nationalism.
Greeters, not guards
Many Americans expected the future to usher in a sense of greater mutual understanding and religious tolerance, said Ed Stetzer, director of the Billy Graham Center at Wheaton College in Illinois. Instead, fear and intolerance seem to dominate the news and social media, with churches, synagogues and mosques increasingly caught in the crosshairs.
"The whole thing with houses of worship is that you welcome people with greeters, not armed guards," Stetzer said. "When you see a troubled person, you think about helping them, not them harming you. We are the perfect soft target."
The attackers in Pittsburgh, New Zealand and Poway are believed to have left behind manifestos outlining white supremacist beliefs, some referencing Christian scripture. But it can be difficult to tell the difference between their ideologies and insincere statements in the manifesto meant to stir up interreligious animosity.
Stetzer said evangelical leaders are beginning to address some white nationalists' "warped" sense of Christianity, but that it can be difficult in a culture increasingly contoured by cable news and "spiritually shaped by social media."
In some ways, the responsibility for addressing the rise in anti-religious violence also belongs to the occupant of the Oval Office, who sets the moral tone for the nation, religious leaders said.
"I am very concerned right now about the political climate we are living in," said Mogahed, "when you have the President tweeting videos of a Muslim congresswoman spliced between the 9/11 attacks and calling asylum-seekers 'invaders."
"When you have that same rhetoric reflected in the manifestos of mass shooters, who even cited our President by name as an inspiration, it is very rational for minority religious groups to be afraid."
Mogahed said her research shows that Muslims and Jews alike share a common threat from white supremacists and have been sounding alarm sirens since the 2016 presidential election.
"There is an empirical link between anti-Semitism and Islamophobia," Mogahed said, noting that the synagogue shooting suspect in California cited the influence of the accused New Zealand mosque attacker. California authorities are also investigating the possibility that the synagogue suspect set fire to a mosque in Escondido last month.
Houses of fear
Among Muslims, Mogahed said many mosques function as "open houses," especially during Ramadan, when strangers from out of town visit to pray.
"It's almost always a mix of strangers and members, and that makes it even harder to notice when someone looks out of place," she said. "So the question then becomes: Are we going to be like airports with metal detectors and security checks at the door? There is a lot of resistance to that."
Imam Omar Suleiman, director of the Yaqeen Institute for Islamic Research, said he hasn't seen American Muslims so anxious since the aftermath of the 9/11 attacks.
"With everything that is happening, I think that every Muslim in America expects a mosque attack to happen in Ramadan," Suleiman said. "Everyone is just wondering how many and who it's going to be."
After the mosque attacks in New Zealand, Valley Ranch Islamic Center in Irving, Texas, where Suleiman is a volunteer scholar, hosted training sessions to prepare for potential attacks. In 2015, armed white supremacists protested outside the center.
"If you are a visible Muslim in America right now, you can expect hostility almost everywhere you go," said Suleiman. "School, grocery store, work -- we always have to look over our shoulder. The mosque had been the one safe place where we could let our kids run around and not worry about them, and we could be fully Muslim and thrive in our identity."
With the recent spate of attacks at houses of worship, Suleiman said, that feeling of safety is gone. "It has robbed the Muslim community of the one safe space it had."
It may be the most prevalent feeling shared among American religious believers today: Their holy places have become houses of fear.