On a chilly November weeknight in a drab apartment building in outer Moscow, seven adults and two small children crowded around a computer screen and sang a hymn as quietly as they could. “Whatever test may come your way, never yield to doubt or fear. Jehovah will provide escape, our God ever will be near!” they chorused.

“At the kingdom hall we liked to sing loudly, but now we can only whisper,” said Yevgeny, who asked his last name be withheld to avoid arrest. “If anything happens, we’re just watching movies with friends.”

Jehovah’s Witnesses, a U.S.-based international Christian denomination claiming 8.5 million members, are a common sight in countries around the world, as proselytizing door-to-door is a central tenet of their faith. But in Russia they have been forced underground following imprisonment and allegations of torture; only Islamic fundamentalists are treated more harshly.

Russia’s justice ministry calls the group, which has grown its membership here to 170,000, a threat to public order. They were banned as “extremist” in Russia in 2017, putting them in the same ranks as neo-Nazis. A spokesperson for the conservative Russian Orthodox Church, which has grown in influence under Putin, has said Jehovah’s Witnesses manipulate people’s consciousness and “can not be called Christians.”

Now, the crackdown is escalating. On Dec. 13, Vladimir Alushkin, an entrepreneur from Penza southeast of Moscow, was sentenced to six years for organizing “extremist activities” after a judge ruled that he had preached the ideas of Jehovah’s Witnesses, organized worship services, distributed literature and gathered donations. Five others including his wife Tatyana received two-year suspended sentences and three years of probation.

“We can’t talk about any sort of justice here,” Tatyana Alushkina told TIME. “This is persecution of the Jehovah’s Witness religion.”

“It’s so difficult for him, but that’s the path of a Christian, and we chose it ourselves,” said Yevgeny, an old friend of Alushkin’s. “We don’t want to sit in prison, but neither did Daniel want to go in the lion’s den.”

Authorities in the U.S. have raised concerns about the worsening treatment of Jehovah’s Witnesses, which comes as Moscow is locked in a geopolitical standoff with Washington. Former Kansas senator Sam Brownback, who now serves as the U.S. ambassador-at-large for international religious freedom, told TIME Alushkin’s conviction was part of a wave of “very aggressive” persecution that led his office to add Russia to its special watch list last year. “You may agree or disagree with their ideology, but they are peaceful practitioners of faith and they are entitled to practice their faith,” Brownback said.

The United Nations office of the high commissioner for human rights previously said that Alushkin’s arrest was arbitrary and discriminatory, calling on Russia to release him.

With roots in a 19th century Bible studies movement in Pennsylvania, Jehovah’s Witnesses are known for a literal interpretation of the Bible as defined by a small council of elders in Warwick, New York, and view earthly governments as controlled by the devil. They believe that Armageddon is imminent and that God’s kingdom will soon be established on earth.

While they have the most “publishers,” or active members, in the United States, Mexico, Brazil and Nigeria, Russia is one of their largest congregations in Europe.

After the 2017 ban, 395 branches of the church in Russia were shut down and their evangelizing and meetings were forbidden. Believers have been forced to gather secretly in apartments, reading prayers and discussing the bible with half a dozen other small groups via video link. Each session starts with an admonition to make sure the door is closed in case someone tips off the police.

The organization says 297 members in Russia are facing criminal charges; 43 are in detention and 22 are under house arrest. At least 5,000 have fled Russia for Europe and North America.

In February, a court in Oryol sentenced Dennis Christensen, a Danish Jehovah’s Witness elder who lived in the country since 2000 and has a Russian wife, to six years in prison. Elder Sergei Klimov in Tomsk was similarly sentenced six years, and six men in Saratov were given terms ranging from two to three-and-a-half years in September

That same month, the State Department placed a U.S. travel ban on two Russian officials for allegedly torturing seven Jehovah’s Witnesses in the Siberian oil town of Surgut. The believers said law enforcement agents had beaten them, administered electric shocks and suffocated them with plastic bags during interrogations. Criminal charges have been brought against four men, and another 17 people are considered suspects, one of them, legal consultant Timofei Zhukov, told TIME.

As part of raids on more than 20 apartments in July, masked agents climbed in through the balcony at 6:20am and tied Zhukov up on the floor, after which one kicked him in the head “as if he was kicking a football,” he said. He says he was held at the investigators’ office for hours as screams echoed down the hall.

“When peaceful people are tortured, it’s fascism,” Zhukov said. “They physical and morally humiliate people so they will deny their faith.”

The brutal repressions have reminded some in the church of when Joseph Stalin sent nearly 10,000 Jehovah’s Witnesses to guarded settlements in Siberia. “For now we don’t have hundreds of people in camps, we don’t have deportation,” said spokesman Yaroslav Sivulskiy. “But we hadn’t heard of torture like in Surgut, how people in masks threw even old people to the ground.”

Sivulskiy spent a year and a half in Soviet prisons for refusing army conscription, a principle that still brings Jehovah’s Witnesses into conflict with the Russian authorities today, as does their opposition to blood transfusions.

Russian President Vladimir Putin has been ambivalent about the ban. Asked about it last year, he said Russia could be “more liberal toward representatives of different religious sects, but shouldn’t forget” that 90 percent of people here consider themselves Orthodox. (Polling suggests the actual number is closer to 75 percent.)

Once a source of support for the tsars, the resurgent Orthodox church has now become a pillar of Putin’s rule, which Patriarch Kirill has described as a “miracle of God,” and of Russian influence abroad. The state gives tens of millions of dollars to the church each year, and the military is building a 300-foot-tall Orthodox cathedral with steps made of melted down Nazi tanks at a patriotic park outside Moscow.

Jehovah’s Witnesses oppose such cozy relations with the state. They do not vote or hold public office, and unlike the Seventh Day Adventist or Pentecostal churches, they have not participated in Putin’s council for cooperation with religious associations. “They try to avoid talking with the government, they don’t participate in councils, they don’t go anywhere, they pay taxes and register and that’s it, and our government is suspicious of this,” said Alexander Verkhovsky, who tracks racial and religious discrimination at Moscow’s SOVA Center.

While the Russian authorities continue to tighten the screws, each arrest only convinces Jehovah’s Witnesses that they are in the right. “Christ said they will persecute you for your faith,” Zhukov said, “and when you see it with your own eyes, you’re even more convinced.”

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