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. 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.
"When a Jew alienates himself from his people, God forbid, it is only because he is thirsty," Schneerson once said. "His soul thirsts for meaning in life, but the waters of Torah have eluded him. So he wanders about in foreign domains, seeking to quench his thirst.
"Only a shepherd who hastens not to judge the runaway kid, who is sensitive to the causes of its desertion, can mercifully lift it into his arms and bring it back home."
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.
