Blumi Lazar’s wedding was not an intimate affair. A thick white dek tichel completely covering her face, Blumi stood under a massive raised chuppah of indigo velvet and gold fringe, swaying ever so slightly next to her groom, Isaac Rosenfeld, before some 1,500 invited guests. Among the sea of black hats and sheitels gathered in Moscow last week were Jews of all stripes: Israeli expats, American expats, wealthy Jews, less-wealthy Jews, secular Jews, half-Jews, Jews who had never left Moscow, and Jews, like me, who had left and come back. There were even non-Jews. And they were all there because Blumi Lazar’s father, Berel Lazar, is the chief rabbi of the Russian Federation, and because right up until the minute before Blumi was born, just a week shy of 20 years ago, such a gathering—a cruise-ship-sized celebration of a religious Jewish wedding in a park that was once the czar’s falconry grounds—would have been impossible.“She was born just before the revolution, in June 1991,” Rabbi Lazar told me after the ceremony as he, his wife, and their new machetunim paced nervously outside the yichud room, where the bride and groom go to spend a few minutes alone. “Before that, people were walking with their heads down, hiding their Jewishness,” he said. “To talk about a wedding in the street—it was unheard of. We feel that these 20 years with her, they’ve been a rebirth.”Berel Lazar was the midwife of this change. Born in postwar Milan, Italy, to parents who were among the first of the Lubavitcher Rebbe’s emissaries to the backwoods of Judaism—“There was no kosher even,” his sister Chani told me—Lazar found the next frontier when he came of age: the Soviet Union. He traveled to the slowly imploding empire in 1987 as a rabbinical student; there he worked to establish underground yeshivas and to help refuseniks make contact with the outside world. By 1989, he had helped open a Jewish school in Moscow. Unfortunately, after the revolution, most of its hoped-for students soon abandoned Moscow and the Soviet Union, their parents deciding against staying in a country that had singled them out—and held them back—for being Jewish. Ironically, those who left assimilated abroad, and those who stayed—often intermarried couples—soon found more and more opportunities to be Jewish and live Jewishly in a country that was also undergoing a Christian revival. (Also, the target of nationalist discrimination shifted from the Jews—most of whom had left—to migrants from the Caucasus and Central Asia.) Whatever one makes of Chabad’s presence in places like American college campuses, the Hasidic group’s impact in Russia has been undeniably positive: Moscow now has three large and flourishing synagogues, not all of which are Chabad-sponsored, Jewish schools and kindergartens, an annual Yiddish Fest to celebrate Purim in a hip, young way, and Chabad representatives in nearly 50 cities across Russia, in strange, small places like Barnaul and Dzerzhinsk and Lenin’s birthplace, Ulyanovsk. And that’s not even counting the missions in the broader former Soviet Union.And so when it was time for the sheva brachot, the seven blessings, at Blumi Lazar’s wedding, the guests who came up to read them and their translations were not personal friends or friends of the bride and groom but allies in Rabbi Lazar’s fight to resuscitate Jewish life in Russia.But the bride had been the guinea pig in that fight, pointed out Riva Zaklos, the wife of the rabbi of Bryansk, a city in Western Russia on the border with Ukraine. (“No one comes to Bryansk,” Zaklos, a native of Israel, told me in Russian. “Every time someone comes, I say, ‘What did you lose here?’ ” She and her husband have scraped together 5,000 Jews there and started a preschool that serves kosher food. There have even been some Jewish weddings.) “Blumi was the first one to go to Jewish pre-school, the first one to go to Jewish school here, and everyone watched her, watched how she did,” Zaklos said, nursing a virgin raspberry mojito. Waitresses circled with hors d’oeuvres, mixing with beautiful women in long, sparkling dresses and a dazzling array of sheitels, wigs, that looked like they were from shampoo commercials. (The men were separated from us by a wall, a mehitsa.)Blumi’s sisters wore salad-green princess dresses; Isaac’s wore navy with beaded accents. “You always need two colors,” Zaklos explained, “one for the bride’s sisters, and one for the groom’s. Otherwise, how can you tell?” The dresses presented another issue: With so many children in each family, there were that many weddings, and you couldn’t, of course, wear the same dress to too many weddings, especially not contiguous ones. “So, we just swap dresses,” Zaklos explained.Behind her, women were discussing complicated fusions of family trees—“No, no, no, Chani’s dad is Berel’s brother-in-law!”—while others carried babies who were either their children or their grandchildren. “You know the difference between religious weddings and Reform weddings?” Chani Springer, Blumi’s aunt and Rabbi Lazar’s sister, asked me. “At religious weddings, the mother of the bride is pregnant. At Reform weddings, the bride is pregnant.”The mother of the bride, Chani Lazar, née Deren, seemed done with that after 12 children. But even after all those kids, she has not lost her girlish figure, hemmed in by a lush mustard-green gown with a fluffy hem that resembled the mouth of a tuba. Her eyes red and moist, she said, “Every mother should be so happy,” and went back to chirping with her friends and micromanaging the proceedings.It was through Chani Lazar that Blumi found her groom: Chani’s sister—also a Blumi—married a man named Yisroel Rosenfeld, and the families became extremely close. In her youth, Chani Lazar used to spend lots of time at the Rosenfeld house. Then one day, Blumi suggested that she had someone in mind for Blumi Lazar: her nephew, the son of the Chabad emissary to Bogotá, Colombia. After a period of discovery and due diligence on each other—“research,” those in the community call it—Isaac flew to Moscow in the dead of the Russian winter to meet Blumi and, after a few meetings, they got engaged.At their wedding, four and a half months later, the two were lost in the swells of infinite family members and friends from around the world, members of the Russian Jewish community, people who were their parents’ friends and allies in Moscow and Bogotá, people whom they probably hadn’t even met. On the jumbo screens in the reception hall—where there was not nearly enough seats for the women—you could see them: Isaac’s black hat lost in a mosh pit of hundreds of dancing black hats; Blumi’s veil over her long blond hair bobbing through the roundelays of women, circling her and cheering. The innermost circle, though, was a group of teenage girls who danced around the placidly happy Blumi. They were her students at the Jewish school, where she has taught Jewish studies for the last two years.Julia Ioffe is a senior editor at The New Republic and formerly Foreign Policy’s Moscow correspondent.