PENDLETON, Ore. — Weeks after President Donald Trump demanded that America’s shuttered houses of worship be allowed to reopen, new outbreaks of the coronavirus are surging through churches across the country where services have resumed.

The virus has infiltrated Sunday sermons, meetings of ministers and Christian youth camps in Colorado and Missouri. It has struck churches that reopened cautiously with face masks and social distancing in the pews, as well as some that defied lockdowns and refused to heed new limits on numbers of worshippers.

Pastors and their families have tested positive, as have church ushers, greeters and hundreds of churchgoers. In Texas, about 50 people contracted the virus after a pastor told congregants they could once again hug one another. In Florida, a teenage girl died last month after attending a youth party at her church.

More than 650 coronavirus cases have been linked to nearly 40 churches and religious events across the United States since the beginning of the pandemic, with many of them erupting over the last month as Americans resumed their prepandemic activities, according to a New York Times database.

“There’s a very fine line between protecting the health and safety of people, and protecting the right to worship,” said George Murdock, a county commissioner in northeastern Oregon, where the largest outbreak in the state has been traced to a Pentecostal church in a neighboring county.

While thousands of churches, synagogues and mosques across the country have been meeting virtually or outside on lawns and in parking lots to protect their members from the virus, the right to hold services within houses of worship became a political battleground as the country crawled out of lockdown this spring. In May, the president declared places of worship part of an “essential service” and threatened, though it was uncertain he had the power to do so, to override any governor’s orders keeping them closed.

But as the virus rages through Texas, Arizona and other evangelical bastions of the South and West, some churches that fought to reopen are being forced to close again and grapple with whether it is even possible to worship together safely.

“Our churches have followed protocols — masks, go in one door and out the other, social distancing,” said Cynthia Fierro Harvey, a bishop with the United Methodist Church in Louisiana, where three churches recently closed again. “And still people have tested positive.”

Other congregations have remained defiant in the face of rising infections, saying state rules limiting service sizes infringe on their constitutional right to worship.

Some Christian groups objected to a new California rule that restricts singing in places of worship. In Nevada, the Calvary Chapel Dayton Valley is challenging state rules that cap religious gatherings at 50 people while allowing casinos and other reopening businesses to operate without similar limits.

“They’re downplaying the role that religion plays in the lives of Americans and suggesting it’s more important to go to the gym than to go to church,” said Kristen Waggoner, general counsel of the Alliance Defending Freedom, a conservative religious-liberty group that brought the Nevada lawsuit and has challenged other state restrictions on religious gatherings.

She said that the vast majority of churches meet or exceed federal health guidelines for reopening.

But as new cases and clusters have emerged throughout the U.S., public health experts have emphasized that, even with social distancing, the virus can easily spread through the air when hymns are sung and sermons preached inside closed spaces. One of the world’s first mass coronavirus outbreaks occurred in a secretive South Korean church.

“It’s an ideal setting for transmission,” said Carlos del Rio, an infectious disease expert at Emory University, referring to church gatherings. “You have a lot of people in a closed space. And they’re speaking loudly; they’re singing. All those things are exactly what you don’t want.”

There were just six recorded cases of the coronavirus in Union County, in rural northeastern Oregon, when the Lighthouse United Pentecostal Church announced its reopening May 22 in an Instagram post that also cited Trump’s remarks about reopening churches.

Now, the county has recorded 356 cases, many traced to the church.

The outbreak is thought to have been seeded by a wedding there, which drew attendees from out of town, said Dan Satterwhite, a pastor at an affiliated Lighthouse Church in the neighboring town of Pendleton. The pastor of the Island City church contracted the virus, and his wife was hospitalized, Satterwhite said.

In his church, Satterwhite said, congregants were social distancing and mostly wearing masks. He had initially livestreamed services on Facebook, but some congregants begged to return to church, and others did not have reliable internet access.

“I am trying to do the right thing. I know a lot of people don’t feel this way, but those that do, feel that church is essential,” Satterwhite said. “There’s more to be considered there than just the physical health; there’s also the spiritual health.”

The outbreak has stoked resentment against the church from residents who believe its members acted recklessly, but some local officials defended the church’s actions.

While major Christian denominations, synagogues and mosques across the country have taken pains to craft detailed reopening plans and impose strict new rules, some of the recent cases appear to have occurred in churches that did not require masks or keep members apart.

In Fort Myers, Florida, Carsyn Davis, a high school orchestra member, attended a youth party at her church June 10 with 100 other children. She did not wear a mask, and children at the event, billed as a “release party” of fellowship and games to celebrate the return of church services, did not stay at a distance, according to a Miami-Dade County medical examiner’s report.

Three days after the party, Carsyn, who had asthma and had overcome a rare neurological disorder as a child, developed a headache, sinus pressure and a mild cough. She died June 23, two days after her 17th birthday.

The church’s pastor, Dustin Zarick, said in a video posted to Facebook that the church had canceled all youth activities because “several families had been affected by COVID-19.” He said the church had made the “proactive decision” in order to keep members safe.

“Media reports and postings accusing the church of ignoring protocols or actively engaging in behavior intended to expose our congregation to the virus are absolutely false,” the church said in an emailed statement.

Satterwhite, the pastor in Oregon, said scrutiny had fallen unfairly on churches, while businesses with outbreaks did not face the same backlash.

“I think that there is an effort on the part of some to use things like this to try to shut churches down,” he said, adding that he appreciated Trump’s supportive remarks about churches.

When weighing his responsibility as a faith leader, Satterwhite said, he returned to his beliefs.

“My personal belief is, I have faith in God,” he said. “If God wants me to get COVID, I’ll get COVID. And if God doesn’t want me to get COVID, I won’t.”