If the non-Jewish public is even vaguely aware of the Chabad-Lubavitch movement, it's probably because its annual telethon draws celebrities including Adam Sandler, Michael Douglas, James Caan, Whoopi Goldberg and Anthony Hopkins. But within the Jewish world, this small branch of Judaism is generating outsized levels of interest -- and concern.
On the one hand, Chabad -- with its rigorous observance of Jewish law and rabbis in long beards and wide-brimmed black hats -- has become an island of growth, innovation and success at a time of aging synagogue memberships and stagnant population elsewhere among American Jews.
On the other hand, there's the matter of the Messiah. Tuesday, thousands of Chabad faithful gathered in the Queens borough of New York at the grave of Rabbi Menachem M. Schneerson to mark the 10th anniversary of his death. Among them were a fair number who believe Schneerson is soon to be resurrected.
Such passion might be ignored by mainstream Jewish leaders if it were not for the remarkable efforts of the Brooklyn-based Lubavitchers to foster Judaism worldwide.
About 4,000 rabbis and their families now serve lifetime assignments in 2,700 posts in 61 countries. The number has roughly doubled in 10 years, Chabad statistics show.
Chabad of Utah was founded in April 1992 as a "gift to Rabbi Schneerson for his 90th birthday," said Rabbi Benny Zippel, who leads Bais Menachem, Utah's only Lubavitcher congregation.
Since then, the group in Utah has swelled to about 100 who regularly attend High Holy Day services, Zippel said.
"I disagree with Chabad about practically everything," Rabbi Eric H. Yoffie, leader of the liberal Reform Jewish movement, said in a speech last year. "But I envy the selflessness of their young men and women who fan out across the world to serve Jewish communities in distress. We must foster among our members the same sense of mission and spirit of service to the Jewish people."
Others rue the spread of Lubavitch influence.
"The Jewish community is becoming deeply dependent on them for religious services and ceremonies, education and social services," said David Berger, an Orthodox rabbi and a history professor at Brooklyn College who has written a book on Chabad. "It's a clear and present danger to Judaism."
The prime issue for Berger and Chabad's other critics is the belief by some Lubavitchers that Schneerson -- the movement's last leader, who died in 1994 at age 92 -- is the Messiah long foretold in Hebrew Scriptures. Chabad's leaders officially reject that doctrine and insist it is fading in their ranks.
"Rabbi Schneerson never wanted his followers to see him as the Messiah," said Zippel, who attended the celebration in Brooklyn. "I looked at him as a figure of incredible source of inspiration and of always seeing the good in every person."
Still, within the movement others fervently embrace it. And outside Chabad, some Jews fear that the organization's growth and vibrancy are merely cover for a sect they see as undermining traditional Jewish beliefs.
Chabad, a Hebrew acronym for wisdom, understanding and knowledge, took root in the late 18th century in the then-Russian city of Lubavitch. It's a form of Hasidic Judaism, which is characterized by its embrace of uneducated Jews, mystical and often ecstatic piety and devotion to a single leader, the rebbe.
Schneerson's father-in-law, who preceded him as rebbe, fled the Nazis and moved Chabad headquarters to Crown Heights, in Brooklyn, in 1940. Shortly after, Chabad began to emphasize reaching out to nonreligious Jews -- a striking difference from other Hasidic groups, which often advise members to isolate themselves from the temptations of the world.
The idea was to patiently and nonjudgmentally lead Jews back to Orthodoxy one small step at a time -- attending a Sabbath service, lighting candles Friday night, listening to a lecture from a Jewish speaker.
The charisma of Schneerson's leadership was such that in the final years of his four decades of leadership, increasing numbers of Lubavitchers believed the rebbe had the potential to be "moshiach," the Messiah.
Messianism -- the belief that God will choose a person to redeem the world -- has been a central element of Jewish belief for 2,500 years. Among many liberal Jews today, the idea has become muted or transformed into the belief that Jews collectively should work to repair the world's ills. But among traditional believers, the imminent coming of the Messiah remains a powerful hope.
From time to time through the centuries, groups of Jews have fastened those hopes on an individual. Two millenniums ago, the followers of Jesus of Nazareth founded the Christian church based on that belief.
When Schneerson died, many expected the whispers that he was "the one" would dissipate: Traditional Judaism holds that the Messiah would be a living person.
Although the belief has waned since the rebbe's death, some believers in Schneerson adopted an idea associated with Jesus: resurrection.
The messianists believe Jews can prepare the way for Schneerson's return by observing the Bible's commands and performing good deeds that will lift the state of the world.
Some critics argue that such beliefs have divided the Chabad movement, but Zippel calls it a "non-issue."
"In the Torah, it is clear that it is up to God and God only who the messiah is," he said, "and when to appoint the messiah."