Patriarch Alexiy II, who died on Friday, had an extraordinary career, in which he switched from suppressing the Russian Orthodox Church to being its champion.
Patriarch Alexiy II was popular among fellow churchmen
A favourite of the KGB, he was promoted rapidly through the Church hierarchy, doing the Kremlin's bidding at a time when dissident priests were thrown into jail.
As the Church's effective foreign minister, he helped cover up the repression of Russian Christians, defending the Soviet system to the outside world.
He rose quickly through the ranks, being elected head of the Russian Orthodox Church at a crucial time, in 1990, with the Soviet Union on the path to collapse.
Surprisingly, perhaps, he seized the moment, and went on to oversee the revival and flowering of the Church, exuding moral authority and inspiring devotion among his followers.
Born Alexei Ridiger in 1929 in Estonia, which was then independent, he had some taste of freedom before the country was annexed by the Soviet Union during World War II.
But his mother was Russian, and he found he had some sympathy with the Soviet cause.
Christ the Saviour Cathedral was rebuilt under Alexiy
As the Soviets tried to soften Estonia up, Ridiger proved to be a key figure, and was appointed Bishop of Tallinn and Estonia at the young age of 32.
In 1986 he became Metropolitan of Novgorod and Leningrad, the second highest position in the Church.
By the time Patriarch Pimen I died in 1990, persecution of Christians in Russia was being relaxed, and the Church was allowed to freely elect his successor.
Ridiger was a popular figure in the Church, and was appointed Patriarch Alexiy II.
Archbishop Chrysostom remarked: "With his peaceful and tolerant disposition Patriarch Alexiy will be able to unite us all."
Indeed he did, overseeing what Michael Bordeaux, founder of the Keston College religious research centre, calls "the remarkable rebirth of the Russian Orthodox Church, and its flowering up to the present day - a real contrast to the first half of his period in office - or two-thirds - working with the Russian authorities to keep the Church down".
A strong, even ruthless leader, Alexiy "performed both roles supremely well", says Mr Bordeaux.
Suspicion of Catholics
The Church benefited from Mikhail Gorbachev's 1990 law, sweeping away Stalinist repression and introducing complete freedom of religion.
In fact, Alexiy felt this went too far, giving Protestants and Catholics a great opportunity to launch missionary work.
Alexiy stayed close to the authorities throughout his life
Later, a new law under Russia's first president, Boris Yeltsin, boosted the Orthodox Church over and above other religions.
Alexiy was determined to keep the Catholic Church, especially, at arms length.
The Vatican was keen to re-establish the widespread presence it enjoyed in Russia before being completely abolished by the Communists - but Alexiy did not welcome this.
There were a number of overtures by the Vatican, and former President Vladimir Putin even invited Pope John Paul II to Russia, but Patriarch Alexiy refused to take part and the visit never happened.
To his own followers, though, he was a unifier, and succeeded in repairing the 80-year rift with the Russian Orthodox Church Abroad.
The patriarch secured Kremlin support for the resurgent Church, and oversaw the full rebuilding of the resplendent Christ the Saviour Cathedral in Moscow, which had been destroyed under Stalin.
Having appointed bishops "very much of his own mindset", the Russian Orthodox Church is unlikely to go through any sudden changes after his death, says Michael Bordeaux.