MOSCOW — A few blocks from Moscow's Lubyanka Building, which for decades served as the headquarters of the Soviet Union's KGB security agency, the Russian Orthodox patriarch recently consecrated a church memorializing those martyred during communism's reign.

"While we were in procession around the church, people were standing with portraits of those martyred and those condemned to death" by the communist regime, said Orthodox Metropolitan Hilarion of Volokolamsk, who heads the church's department for external affairs.

President Putin, who was a former KGB agent, as well as government officials and church leaders, were in attendance for the ceremony May 25.

Patriarch Kirill's consecration of the Church of the New Martyrs and Confessors of the Russian Orthodox Church was one of the ways his church is commemorating the centenary of the 1917 Bolshevik Revolution, which ushered in the communist era and led to the persecution of Christians.

The 100th anniversary of the communist takeover of Russia coincides with the 100th anniversary of the final apparition of Our Lady of Fatima to three shepherd children in Portugal. The children said the lady "dressed in white" asked them for prayers and penance, otherwise Russia "will spread her errors throughout the world, causing wars and persecutions of the church."

The Russian Orthodox Church formally has recognized or "glorified" more than 1,500 bishops, priests, monks, nuns and deacons who died for their faith under communist rule, which lasted from 1917 until 1991. While the Orthodox Church was never legally suppressed like most Protestant churches were, communist authorities worked vigorously to encourage atheism, closing thousands of Orthodox monasteries and churches, sending clergy and religious to the gulags or to psychiatric hospitals, and making it extremely difficult for any regular churchgoer to hold a decent job or get into a university.

The Roman Catholic Church suffered even more. Long considered by Russians to be part of the West, under communism, Catholicism was seen has having a foreign allegiance. By the end of the 1930s, only two of the 150 Catholic parishes in Russia were still functioning. And, with the establishment of the Soviet Union — and its incorporation of neighboring republics — the persecution grew. The Ukrainian Catholic and other Eastern Catholic churches were outlawed, and their bishops were imprisoned. Priests caught celebrating Mass were arrested and either executed or sent to prison or to work camps.

After the Soviet Union began breaking up in 1990 and communist rule came to an end, all of the churches experienced a revival. In Russia, even government officials are now embracing Orthodoxy in public, and Russian culture and art are being transformed with new Christian influences.

Salavat Scherbakov, a Moscow-based sculptor, recently completed a massive statue of Russia's first Christian emperor. The towering St. Vladimir sculpture was prominently placed in Borovitskaya Square, just outside the walls of the Kremlin.

"We are coming back to our roots," Scherbakov said. "We still do not understand these roots well enough; it is a kind of a new search for identity."

Despite the collapse of communism and the renewed prominence Christianity enjoys in Russian society, Metropolitan Hilarion sees a host of new challenges facing the Orthodox Church today.

"The challenge of secularism, of secularist ideology, of consumerism," is among the biggest threats facing his church in Russia today, Metropolitan Hilarion said.

Other Orthodox believers identify different risks to the faith in modern Russia. Chief among their concerns is the increasing collaboration between church and state.

For example, some politicians defend religious traditions alongside the values of Soviet communism as part of a wider patriotic celebration of Russia's past, said Sergey Chapnin, the former editor of the Journal of the Moscow Patriarchate.

"You have this merging, a kind of melting pot where we have Christian tradition and Soviet tradition being put together, and this is a kind of post-Soviet civil religion," Chapnin said.

Chapnin described this "civil religion" as one that emphasizes Orthodoxy as a marker of national identity, rather than the "life of the real church." Even if it also stresses "traditional values," the concept is too nebulous to reflect the actual teachings of the church, Chapnin said.

Legislation promoting the family and pro-life causes may be examples of traditional values, "but when we are trying this stuff as state policy or the political program of the ruling party, we face serious problems because people are not ready" to accept these teachings, Chapnin said, noting that the number of weekly Orthodox churchgoers in his country remains very small.

According to a recent study from the U.S.-based Pew Research Center, only 6 percent of the Orthodox population in Russia attends church weekly.

Yet some observers argue that such statistics do not adequately reflect the true extent of religious commitment in Russia.

"Going to church in Russia is very different from going to church in America," said Mother Cornelia Rees, an American Orthodox nun who has lived in Russia since 2008.

"Going to church is not just a Sunday morning thing for an hour or so," but involves a three-hour vigil the night before, going to confession, fasting from meat and dairy products and reciting pre-Communion prayers as prerequisites for receiving the Eucharist.

"So if you take a survey, you'll probably get a lot of people" who identify as Orthodox but say they are not churchgoers, Mother Rees said. "They go to church every now and then, and they consider themselves an Orthodox Christian, but they are not doing all these various things."

Church attendance among self-identifying Roman Catholics in Russia is not much better, according to the country's most senior archbishop.

"In our diocese there are 250,000 Catholics," said Archbishop Paolo Pezzi of Moscow, though "in Russia, like anyplace else, there is a difference between those who declare themselves Catholics and those who really practice the faith."

"I suppose that the number of practicing Catholics is 10 to 20 percent of all nominal Catholics in Russia," he said.

Today, the Catholic Church in Russia enjoys cordial relations with the Orthodox, and "our relations are improving on all levels," Archbishop Pezzi said, pointing out that he is regularly invited to join the Orthodox patriarch of Moscow at Christmas and Easter liturgies.

"Today, we can call each other not only partners, but also friends and even brothers, though we understand that we still lack full communion in the sacraments," Archbishop Pezzi said. "There is still a long road ahead of us."

Notwithstanding the challenges believers face in Russia today, many Orthodox faithful are optimistic about Christianity's future.

Soskina Lubov Stepanovna, 68, who has lived her entire life in Nizhniye Pryski near the famous Optina Pustyn Monastery, remembers the decades when going to church was illegal.

"Now life is better: We can pray, ask God for help and he listens to our prayers and helps us. We ask him to help our children and, you see, our children were baptized as Christians," she said.

Mother Rees said that, despite the progress made since the fall of communism, the country still suffers "ills" left from its atheist past, reflected in high rates of abortion, prostitution and drug addiction.

"We are talking about a society that for 70-odd years, the church was under severe repression," she said. "Things don't happen all at once."