To the outside observer, the haredi Orthodox anti-Internet rally at New York’s Citi Field may have looked uniform: a single mass of black hats, white shirts and brown beards.

But the crowd at Sunday's event was far from homogeneous.

Yiddish speakers sat next to Anglophones. Chasidim from Brooklyn mixed with “yeshivish” haredim (non-Chasidic) from Lakewood, N.J. Bobov Chasidim cheered along with Satmars. These groups, while similar in many ways, usually stay within their own communities.

But it’s hardly the first time the haredi community has faced a threat from the outside world.

As speaker after speaker at the rally made clear, the Internet is the latest in a series of threats dating back to the Jewish Enlightenment, or Haskalah, which first opened up a path for Jews to leave tradition for the secular world.

“Just as they fought tooth and nail against the Haskalah, they’re fighting again against this,” said Samuel Heilman, a professor of sociology at the City University of New York who studies haredi communities. “They live in a singular world. They've tried to keep all the doorways locked from the inside, but you can only lock something from the inside if the people are willing to keep it locked.”

Wachsman and others made clear at the rally that they view the Internet as a profound challenge to the haredi way of life.

“This issue is the test of the generation that threatens all of us,” Wachsman said. “Your strength at this gathering will determine what we look like a few years from now.”

At the same time, the Internet has become a necessity for many, if not most, haredim: They use it to conduct business, communicate with each other and even to promote Jewish observance.

“In the sense that they have already used the Internet to spread their message far beyond the local community, the Internet has been good for them as well,” Heilman said. “They’re going to use it, going to say that the end justifies the means.”

The late Lubavitcher rebbe, Menachem Mendel Schneerson, famously embraced technology as a means of spreading the faith. The Chabad-Lubavitch movement, which did not officially participate in the rally, was an early adapter to the Internet age and has used online tools to spread its message.

"Everything God created in this world could be used for good or the opposite," said Rabbi Zalman Shmotkin, director of Chabad.org. "It's our responsibility to channel the enormous powers of technology in a positive manner."

But the Internet’s dangers -- not just pornography and the window it provides into the secular world, but even its potential for distraction -- present the haredi lifestyle with the challenge of how to use it for good while keeping out the bad.

The haredi community is not alone in this struggle.

Jason Miller, a Conservative rabbi who maintains an active Web presence, said the Internet challenges anyone who cares about ethics.

“To some extent, we all need to have the Internet moderated for us,” Miller said. “Beyond modesty, there’s content that I don't think is healthy or beneficial for individuals to see or read.”

Adrianne Jeffries, a female blogger who snuck into the rally disguised as a man, wrote that although not haredi, she found herself agreeing with some of the speakers’ points at the rally.

“There wasn’t much I could quibble with in the speech,” wrote Jeffries, who blogs for BetaBeat, a technology blog associated with The New York Observer. “The Internet is about instant gratification? It’s “fleeting and empty”? It causes us to waste productive hours? It threatens the preservation of isolated communities with strong traditions, such as the ultra-Orthodox Jews? Well, yes, but …”

For a community whose survival depends in part on maintaining its isolation, the Internet can be particularly pernicious.

“Jews should separate themselves from the general community,” Rabbi Yechiel Meir Katz, the Dzibo rebbe, said at the rally. “The great rabbis have done so in order to safeguard future generations.”

Even as he delivered his speech -- in Yiddish that ran with English subtitles on Citi Field’s JumboTron -- many in the crowd could be seen thumbing their BlackBerrys or iPhones.

“The battle against the Haskalah they lost,” Heilman said. “It's clear that they've lost this one already.”

Alan Mittleman, a professor of Jewish thought at the Conservative movement’s Jewish Theological Seminary, said that on the contrary, the haredim are winning the battle against the Internet just as they survived the Haskalah.

“It’s a problem that they've already solved,” he said of the Internet. “It’s more powerful and invasive, a new kind of threat, but it’s the same kind of thing.”