(CNN) Bomb threats at more than 100 Jewish Community Centers . Dozens of mosques vandalized and attacked . Shootings at churches across the country, including on November 5 -- when a gunman shot and killed more than 20 people at First Baptist Church in Sutherland Springs, Texas , during the morning worship service.

Reading the headlines, you might get the impression that sacred spaces are increasingly unsafe and that religion itself is under attack in America.

Understandably, that's how many Christians, particularly Southern Baptists, seemed to feel after the November 5massacre at First Baptist in Sutherland Springs. The attack targeted more than a single congregation, wrote one prominent Southern Baptist . It was an assault on Christianity itself.

But most attacks at houses of worship aren't really about religion, experts say. And even with the steady rise of shootings and hate crimes, spiritual sanctuaries remain among the more secure spots to spend a Sunday morning.

"It's very safe to go to church on Sunday," said Dallas Drake, a criminologist at the Center for Homicide Research in Minneapolis. "There are very few incidents, but they are high-profile when they occur."

Drake likened church shootings to mass murders at schools: They are horrific because of who and what they target, but they are also relatively rare.

Drake and a team of scholars compiled a database of all church shootings between 1980 and 2005. (It did not include shootings from other houses of worship such as temples or mosques.)

Jarringly, most victims of church shootings likely know their attacker. Nearly half of the offenders (48%) were affiliated with the church, according to Drake, and nearly a quarter (23%) involved "intimate partners," such as wives, girlfriends and husbands.

Earlier on November 5, Devin Patrick Kelley, the shooter in Sutherland Springs, had texted threats to his mother-in-law, who regularly attended First Baptist, authorities said. She was not inside when Kelley opened fire in the sanctuary, police said.

"This was not racially motivated. It wasn't over religious beliefs," said Freeman Martin, regional director of the Texas Department of Public Safety. "There was a domestic situation going on with the family and in-laws."

Unwelcome or mentally ill

In 17% of church shootings, the attacker felt unwelcome or had been rejected by the church, Drake said. Twelve percent of the shooters suffered from a mental illness.

Those statistics jibe with more recent data from Carl Chinn, a church-security consultant based in Colorado Springs, Colorado. Chinn has collected data on more than 1,600 "deadly force incidents" since 1999 at all houses of worship, including mosques, synagogues, etc.

In Chinn's dataset , robberies account for more than a quarter of homicides within houses of worship, followed by fights between domestic partners (16%) and personal conflicts between people who do not live together (14%).

Like Drake, Chinn found that more than 10% of all homicides at houses of worship involve mental illness. Religious bias accounted for about 6%. (In Drake's study, "religious differences" accounted for 9% of church shootings.)

Both Chinn and Drake found that deadly attacks at houses of worship have increased in recent years.

Drake counts 147 church shootings from 2006-2016. Looking more broadly at all violence at all houses of worship, Chinn has tallied more than 250 incidents each in 2015 and 2016. Through August, there had already been 173 this year, according to Chinn. That, of course, does not include the Sutherland Springs massacre on November 5.

But Drake cautions against over-interpreting the increase in church shootings. People of faith are not being targeted because of their religion, he said. Rather, the shootings are part of an overall -- and alarming -- increase in mass shootings within the country at large.

In some ways, Drake said, houses of worship are simply the most "convenient venue" for attackers who harbor grudges against former lovers, spouses or friends. Many sanctuaries have regular schedules, lack robust security and proudly bear open-door policies. They are designed to attract the least and the lost, and to welcome them into a loving community, even if that sometimes has terrible consequences.