A pro-Russian rebel fighter wearing a dog tag and cross in the Baptist Church of Christ in Donetsk, Ukraine, Feb. 24, 2015. Francesca Volpi for Al Jazeera America

DONETSK, Ukraine — Since the pro-Russian separatists declared this region the Donetsk People’s Republic last April, Leonid Krezhanovsky, the leading elder of the Church of Christ congregation, has been looking over his shoulder. The Russian-backed rebels quickly made the Russian Orthodox Church the official religion of the self-declared rebel government. Since then, any religious group outside the Russian Orthodox faith — including Ukrainian Orthodox churches rejecting the Moscow patriarch for the Kiev patriarch — has been viewed by the rebels as a potential enemy of the Donetsk People’s Republic. The resurgence of religious persecution has many people like Krezhanovsky on edge. Armed rebels have arrested Protestant and Catholic leaders in Donetsk and other rebel-held cities, accusing them of being agents for the West or spies for what they say is Kiev’s fascist government. Several religious leaders or followers have been beaten and thrown in KGB-style basement prisons.

Leonid Krezhanovsky, the priest for the Church of Christ in Donetsk. Francesca Volpi for Al Jazeera America In the Petrovsky district on Donetsk’s western edge, rebels ransacked the Jehovah’s Witnesses hall last summer and took over the Baptist church just down the road from the Church of Christ’s small building. With this happening around him, Krezhanovsky, a 63-year-old priest and former mining engineer, wasn’t taking any chances. For most of August and September, he went into hiding. Moving from one relative’s apartment to another across the city, he dodged the rebels’ search for him and other non-Orthodox religious leaders. But in October, they hit him where it hurt most. “I got a call saying a group of rebels were trying to break into our church, so I ran right over there,” he said. “When I saw them trying to break down the door, I offered them the keys. It’s better that they go in peacefully than destroy what we had.” Once inside, the rebel’s commander said they would be taking over the premises because the Church of Christ was accused of being an American operation, according to Krezhanovsky. About a dozen rebel fighters moved into the 3,000-square-foot building, where they camped out in the congregation hall and tossed their Kalashnikov rifles on the wooden altar. He was allowed to pack some of the church’s Bibles and Sunday school books in a back storage room for safekeeping as the rebels made themselves at home in the church’s kitchen and other facilities. Two weeks later, the commander called Krezhanovsky and said his fighters had received orders to move out. Before leaving, they painted a black skull and crossbones and the name of their battalion, “Oplot,” in large letters on an exterior wall. But the church’s liberation didn’t last long. Another rebel group showed up three weeks later, demanding that the priest hand over the keys. This time, the commander was more aggressive and had more fighters with him, Krezhanovsky said.

A rebel fighter carrying a live round through the Church of Christ in Donetsk. Francesca Volpi for Al Jazeera America

“We are unfavorable to the current rebel regime,” he said. “It’s becoming worse, and I predict it will continue to get worse, because this war does not look like it will end soon.” The separatists fighting the Western-leaning government in Kiev subscribe to an ideology that includes a strict adherence to the conservative Russian Orthodox faith. In rebel leaders’ speeches and propaganda, the Russian Orthodox Church is presented as an inherent part of the culture and history of the Donbass. It is one of the driving forces behind the rebels’ greater ambition of building Novorossiya, or New Russia, a territory that includes all of southeastern Ukraine. As the rebel rhetoric goes, given that the Donbass is Russian Orthodox land, it can’t be united with the western parts of Ukraine, where more liberal, permissive religions of Western Europe dominate. Religion in eastern Ukraine’s nearly yearlong conflict has played such a dominant role in the propaganda that there is a rebel battalion called the Russian Orthodox Army. Russian Cossacks at checkpoints across the region say they are God’s defenders of the Russian people and proudly show the crosses around their necks and copies of gilded icons in their pockets.

Krezhanovsky, center, in front of his church, now under the authority of pro-Russian separatists. Francesca Volpi for Al Jazeera America

Books left at the Church of Christ, behind a rebel fighter. Francesca Volpi for Al Jazeera America The use of the Russian Orthodox church in the separatists’ ideology comes out of a playbook being used by Russian President Vladimir Putin and Russian nationalists, who use the faith to rally support for Kremlin moves to re-establish Russia as a great world power, according to Anton Shekhovtsov, a researcher at the University College London who specializes in Russian and Ukrainian nationalist groups. “It’s like a sort of Russian Zionism,” he said. In the Soviet Union, there was an ideology to cling to, but in post-Soviet Russia there is only an authoritarian kleptocracy, he said. “So Putin and the establishment in Russia have to present their followers with something they can use as their identity,” he said. “They can then use this identity to consolidate support and maintain power.” While rebel leaders have insisted that their government is tolerant of other religions, ethnicities and languages, religious leaders like Krezhanovsky say things are very different in practice in Donetsk. Thousands of Jews, Muslims and other religious minorities have fled rebel-controlled territories out of fear of the fighting and persecution. Many churches, including the Church of Christ, have been damaged in the shelling and heavy artillery. The churches that have not been taken by the rebels operate in secret or have simply shut their doors.

St Joseph’s Roman Catholic Church in Donetsk recently reopened and occasionally holds services. Francesca Volpi for Al Jazeera America

In late July 2014 the bodies of four sons of an evangelical priest were discovered in a mass grave in Slovyansk in eastern Ukraine. Locals said rebels murdered them because their church was accused of being American and then buried them together with several other victims during the separatists’ three-month occupation of the city. More than half the Church of Christ’s 200 parishioners have fled. Still, Krezhanovsky leads three services across the city on Sundays, each one in a crowded living room of a member’s apartment. He said he stayed in Donetsk to help other Christians who needed him and he warns them to temper their conversations about religion and political views when riding the bus or standing in line. Living in secret like that reminds him of the Soviet Union, where there was no religion, only “communism and atheism,” he said. Before the conflict started last year, post-Soviet Ukraine enjoyed roughly 23 years of religious tolerance, he said. When the Soviet Union broke up, a diverse number of religious were able to practice openly after years of being suppressed by the communist government. Greek Catholics, Baptists, evangelicals and Jews opened new churches or reopened shuttered ones. According to the Ukrainian Ministry of Culture, 42 percent of the registered religious groups in the Donetsk region in 2014 followed the Russian Orthodox Church’s Moscow patriarch, and the rest were a diverse range of evangelicals, Jews, Muslims, Protestants and others. Nationally, 37 percent of the country’s religious groups were affiliated with the Moscow patriarch.

A separatist fighter in the church kitchen. Francesca Volpi for Al Jazeera America