A former Russian Orthodox cathedral that was converted into a museum of atheism during the Soviet period is to be returned to the Church – and local people are protesting the move.

More than 100,000 people signed a petition on change.org against the return of St Isaac's Cathedral in St Petersburg. Built between 1818 and 1858 by French architect Auguste Ricard de Montferrand, it was formerly the flagship church of Orthodoxy in Russia.

The building is now used for concerts and is a major tourist attraction though religious services are occasionally held there. According to AFP the petition has been driven by fears that access to it will be limited if it is restored to its religious use. More than 3.9 million tourists visited the cathedral last year, earning it more than $13 million in revenue.

The Russian Orthodox Church, which has grown increasingly influential under the rule of President Vladimir Putin, petitioned for the return of the building in 2015 but was turned down by the authorities.

However, the decision was made on Tuesday to agree to the restoration, part of a pattern of restoring churches and monasteries expropriated during years of official hostility to religion. Since the accession in 2009 of Patriarch Kirill, a Putin loyalist, around 5,000 more churches have been built or recovered from secular use, 10,000 more clergy have been recruited and 122 monasteries have been founded. In Moscow, 160 new parishes have been founded.