In its shadow, on nearby Bolshaya Bronnaya Street, a little peppermint- coloured building has also reverted to the use for which it was intended. The Chabad Lubavitch Synagogue may not be as impressive as the cathedral but, for Jews living in this predominantly Christian country, its restoration is no less of a miracle.
Rabbi Moshe Hazan was murdered by the secret police on the steps of the synagogue in 1939. "They wanted him to say that Soviet culture was sufficient to satisfy the soul," says Rabbi Isaac Kogan, who now leads the community.
"But he would not bow to them. They killed him. And the synagogue was turned into a Soviet culture club. Here in this building they used to plan the May Day demonstrations through Red Square."
In 1988, to mark the 1,000th anniversary of the coming of Christianity to Russia, Mikhail Gorbachev eased the restrictions which the atheist Soviet state had placed on the activities of all religious believers.
The Lubavitch community appealed for the return of their synagogue in 1990 and got it back in 1991, since when they have been restoring it.
Rabbi Kogan takes me on to the women's balcony, from where I can see the men gathering below to celebrate the Sabbath. "The Soviets used this as a theatre," he says, pointing to the temple, beautifully restored with dark wood and stained glass. "And now I must go down and you must stop taking notes."
For the sun had set on Friday evening. The Sabbath had begun and work must cease. I stand observing the chanting of the prayers.
Chabad Lubavitch is a Hasidic sect, whose members observe strict kosher rules and still arrange marriages. The men are distinctive in their black hats and long beards and married women wear wigs as a sign of modesty. They believe their last Grand Rabbi, Menachem Schneerson, who died in Brooklyn in 1994, is the Messiah.
Of the world's 14 million Jews, they are a small minority. But in the former Soviet Union the sect is playing a role out of proportion to its size. Liberal Jews in the West were active in trying to help refuseniks reach Israel in the Communist era. But it is the charismatic Lubavitch, regarded with a degree of suspicion by secular Jews, who are trying to rebuild religious life for the perhaps 1.5 million Jews left in the old empire after the waves of emigration.
Much of their funding comes from Levi Levayov, a diamond merchant originally from the Central Asian republic of Uzbekistan. They have penetrated to such an extent that in 20 cities of the former Soviet Union the Lubavitch rabbi is the only Jewish presence. Altogether, 40 Lubavitch and 40 Orthodox rabbis work here. There are no permanent representatives of other sects.
The Orthodox synagogue in Moscow operated in Soviet times when the Chabad Lubavitch one was still closed. Just as Christians made greater or smaller compromises with the Communist state, which allowed believers to worship but not spread religion through education or works of charity, so the Jews either found a modus vivendi with the authorities or became dissidents.
"Judaism is very flexible but we could never accept the ban on teaching our children Hebrew," says Rabbi Kogan, who chose the dissident path. Formerly an engineer in the atomic-submarine yards of what was Leningrad, he was denied exit to Israel for 14 years on grounds he knew state secrets. He became an underground community leader, following in the footsteps of his grandfather, who in the 1950s died of a heart attack in the custody of the NKVD which had arrested him for baking matzo. Only in 1986 did Rabbi Kogan reach Israel.
A small number of Jewish emigres have returned to Russia, dissatisfied with life in Israel. Rabbi Kogan came back for different reasons. "Israel is my dream, today more than ever before," he says. "It is a real holy land." But Lubavitch elders had other ideas for his career. First they asked him to return to work with child victims of the Chernobyl nuclear accident. Then he took over at the synagogue, which runs a school and engages in charity. The rabbi shows me lists of Moscow pensioners, not exclusively Jews, who receive food parcels from the synagogue.
The rabbi is clearly loved by his congregation. "He's so kind. I'm worried stiff about my sister, who lives on the border with Lebanon, and he's promised to take a letter to her when he travels to Israel," says Yevgenia Gutson, an elderly woman who has only recently begun practising her religion.
"I was afraid to be an active Jew under Communism," she explains. "I could have lost my teaching job [in a state primary school]. Of course, I never learnt Hebrew. I have to rely on the Russian translations." That fear of the state has gone. Says Rabbi Kogan: "I define anti-Semitism as forbidding a Jew to express himself in a Jewish way. I do not see that here any more. After decades of spiritual hunger, there is real religious freedom in Russia. Of course, some Jews are still unhappy but if they are leaving now, it is for economic reasons."
He admits, however, there have been attacks on the synagogue, including a fire bomb in 1993 which burnt his bedroom, by "nationalist hooligans who are clearly a minority of the population. Freedom is a two-sided coin. If we have freedom, then the hooligans have it too".
Extreme Russian nationalists identify strongly with the Orthodox Church, even if the hierarchy distances itself from them. The rebuilding of Christ the Saviour Cathedral has been controversial, with many Muscovites saying the money would have been better spent on social welfare. Some liberals fear the opening of the cathedral could encourage dark, chauvinist elements of society.Reuse content