For almost 1,000 years, Christianity in Russia was synonymous with the Russian Orthodox Church, and most of the Russian people were Orthodox believers.
However, from the time when the Bolsheviks seized power in 1917 and established the officially atheist Soviet Union (USSR), until 1990, believers were persecuted, priests were murdered or sent to Siberia, tens of thousands of churches were confiscated by the state, schools and monasteries were forcibly closed, and religion was treated as a legacy of the medieval past which would certainly die out.
Marx's doctrine, "Religion is the opium of the people", was implemented as state policy by Lenin, the founder of the Soviet Union, and his successors.
Churches were tightly controlled. All clergy had to be registered with the regime which controlled appointments, from the lowest level of parish clergy to the Patriarchate. Those churches which refused to accept government control – including the Catholic Church, the Baptists and others – were suppressed.
The Russian Orthodox Church was reduced to the status of a minor department of state. Its few seminaries were closely controlled, and its hierarchy forced to applaud the actions of a regime which had tried systematically to destroy it.
In the international arena, the Russian Orthodox Church sponsored the Christian Peace Conference, part of the Soviet Union's international propaganda offensive designed to convey the impression that the USSR was a tolerant, peace-loving nation – while the regime bankrolled revolutionary movements throughout the world, including in Australia.
After the collapse of the Soviet Union in 1990, governments relaxed controls on the main churches – evangelical and protestant churches continue to be the subject of discriminatory laws – and there has been an astonishing revival of religious belief and practice, and likewise throughout the former Soviet bloc, including Poland, Hungary and the Baltic States (Latvia, Lithuania and Estonia).
In Moscow, a symbol of the religious revival was the rebuilding of the Cathedral of Christ the Saviour in Moscow. In 1931, the Soviet dictator Joseph Stalin had ordered the destruction of the former Cathedral during one of the Soviet's anti-religious purges. It was blown apart with dynamite in December that year.
The site, located close to Red Square, was to be used for the construction of a Stalinist monstrosity, the Palace of the Soviets, topped by a gigantic statue of Lenin. However, attempts to erect the new building repeatedly failed, due to water in the foundations, and after World War II, a later Soviet leader erected the Moscow swimming pool on the site.
After the collapse of communism, the Russian Orthodox Church petitioned for the return of the site, and permission to rebuild the cathedral was given in 1990. A fund to rebuild the cathedral, from the outside a replica of the original, was started in 1992, and over one million Muscovites contributed. This was a clear sign of a rebirth of religion in Russia which had been oppressed and driven underground, but never died.
The Cathedral was consecrated on the Feast of the Transfiguration in 2000, and is the largest church in Russia.
The Cathedral of Christ the Saviour is just the largest of the churches built in Russia over the past 24 years. Since the fall of communism, around 30,000 new Russian Orthodox churches have been built.
At a time when the West has become increasingly secular, there has been a strong growth in religious belief and practice in Russia. In 2011, a survey of religious belief in the country showed that 82 per cent of Russians described themselves as believers, and 13 per cent said they were atheists.
This puts the level of religious belief in Russia higher than in any country in Western Europe.
However, the effect of over 70 years of official atheism is that most Russians have little real knowledge of Christianity, although they have a deep attachment to traditions which Russian Orthodoxy embodies. While most of Russia's believers are Orthodox, about a quarter of believers said they did not regard themselves as members of any particular faith.
The increasing influence of religious belief in Russia is seen in many ways. Russian leaders such as Vladimir Putin and Dmitri Medvedev are frequently seen attending sacred liturgy, particularly on the great feast days of Christmas and Easter.
The Russian Orthodox Church has been one of the principal defenders of marriage, and so the push for same-sex marriage has made no headway in Russia. Further, laws have been carried by the Russian Parliament prohibiting homosexual propaganda directed at young people, with the strong support of the Church.
The Russian Orthodox Church has also pushed the secular education bureaucracy to introduce religion classes in schools.
The result of this is that in all Russian primary schools, the government has introduced religion classes, with parents being given six choices ranging from secular ethics and Orthodox Christianity to Judaism and Islam.
The Church has also pushed strongly for restrictions on abortion which were legally available in the Soviet Union, and are a major contributor to the country's demographic crisis. Although official figures are not available, it is widely recognised that there are almost twice as many abortions in Russia as live births.
Abortion rates in Russia were, for many years, the highest in the world. A leading Russian gynaecologist in 2001 said that there had been over 2.1 million abortions, at a time when the number of live births was just 1.3 million.
Archpriest Dmitri Smirnov, Head of the Patriarch's Commission on the Family, said recently, "In order to change the demographic situation in Russia, it is enough that every child conceived be born. Then the whole [demographic] issue will just disappear."
The population of Russia peaked at about 148 million in 1994, and over the next 15 years, fell by five million to 143 million.
In 2011, the Russian Parliament passed a law restricting abortion to the first 12 weeks of pregnancy, and several other laws have been introduced to make it less socially acceptable.
Former President Dmitri Medvedev introduced a law requiring abortion providers to devote 10% of advertising costs to describing the dangers of abortion to a woman's health and making it illegal to describe abortion as a safe medical procedure.
In conjunction with the Russian Orthodox Church, the president's wife Svetlana Medvedeva, who set up the Foundation for Social and Cultural Initiatives, launched a national campaign against abortion called "Give Me Life!"
Since 2009, the population of Russia has begun to increase again, and is now approaching 145 million, due to the strong pro-family policy being pursued by the government, supported by the Russian Orthodox Church.