Under the watch of Russian police, a group of activists knelt on the icy paving stones outside St Isaac’s Cathedral in St Petersburg to recite article 14 of the Russian Constitution that guarantees the secularity of the state.

Flash protests like these have erupted in St Petersburg since the city government announced this month that it would transfer use of the iconic, 19th-century cathedral and Unesco world heritage site to the Russian Orthodox Church.

More than 190,000 people have signed an online petition addressed to Russia’s president Vladimir Putin and Georgi Poltavchenko, the governor of St Petersburg, demanding that the handover of St Isaac’s to the orthodox church be stopped.

Once a place where the tsars came to worship, St Isaac’s ceased to function as a church after the Russian revolution in 1917 when the Soviets declared war on religion. Looted for gold and precious ornaments, the magnificent domed building was turned into a museum of atheism.

Russian Orthodox services gradually resumed after the Soviet Union collapsed, but St Isaac’s, owned by the government of St Petersburg, has officially remained a secular museum.

Restitution laws

With recent Russian restitution laws expanding its reach, the church has been angling for control of the cathedral. The St Petersburg government has fought back, saying it can’t afford to lose the revenue from ticket sales at a building that attracts more than 3.5 million visitors each year.

The stalemate came to a sudden end this month when Poltavchenko signed an agreement transferring use of St Isaac’s to the orthodox church rent free for 49 years. Ownership of the cathedral will remain with the city government to comply with Unesco rules that world heritage sites be state held.

Russian orthodox clergy have been rejoicing, saying the return of the famous cathedral – coinciding with the centenary of the Russian revolution – should be seen as an act of reconciliation and a tribute to the hundreds and thousands of Russians persecuted during the Soviet era for their religious beliefs.

St Isaac’s is “one of the symbols of Russian orthodoxy and of Russia’s resurrection”, wrote Alexander Pelin, an archpriest in the diocese of St Petersburg. “When the church is returned it will mean the return of the spiritual culture of our ancestors.”

Whatever the spiritual benefits, the transfer of St Isaac’s to the church will leave city government with a big hole in its budget.

“The church wants to make use of the cathedral free of charge while taxpayers pay for the maintenance and restoration of the building,” said Boris Vishnevsky, a deputy for Yabloko, a liberal opposition party in St Petersburg’s legislative assembly. “It’s a wonderful state-church partnership.”

Protest march

Yabloko has teamed up with three other Russian opposition parties to fight for St Isaac’s to stay secular and is planning to lead a march of 5,000 protesters on to the streets of St Petersburg this weekend .

The dispute over St Isaac’s is more about greed than religious revival, according to Dmitri Gudkov, an independent deputy in the Russian State Duma or parliament. “Unfortunately, this story is in fact about faith, not only in God, but Mammon,” he wrote on Facebook.

So far the Kremlin has stayed out of the conflict. Dmitri Peskov, Putin’s spokesman, last week said it was for the St Petersburg authorities to decide the future of St Isaac’s.

However, many commentators believe that the scales in the dispute tipped in the church’s favour after Patriarch Kirill of Moscow and all Russia, a close ally of Putin, visited Poltavchenko, the governor, late last month.

By law Russia is a secular country where there is a strict separation between the state and the church and people from different religions are equal before the law. But Kremlin critics say Putin has drawn the church into an alliance where state authority and the dominant Christian orthodox faith are, as in tsarist times, central to Russian political control and identity.

Reclaimed churches

St Isaac’s is far from the first church to be returned to ecclesiastical use since Russia adopted sweeping restitution legislation in 2010 allowing the orthodox church to reclaim ownership or lease free of charge religious properties and organisations closed after the 1917 revolution.

In St Petersburg alone the church has taken over more than 50 religious buildings in the name of restitution, including the exquisite 18th-century Smolny Cathedral.

Conservationists have criticised the church’s treatment of reclaimed properties, alleging that the restoration of some religious artworks has been botched and ancient churches left to rot.

Many of the museum staff at St Isaac’s share these concerns and dread the arrival of their new employers.

“Far from all employees in state cultural institutions are prepared to become workers of a religious organisation,” the Russian Union of Museum Workers said in a statement.