"We're going to push them back," he says to a chorus of alleluias. "Lord, save us from the Shopocalypse. Can we do it? Someone say, 'Alleluia!'" The crowd obliges. "Blessed are those who forgo the Gap, because they will save our city."
Reverend Billy is the head of the Church of Stop Shopping. He is not a real reverend. His real name is Bill Talen and he is an actor who mixes the manner of an evangelist preacher with the message of anti-globalisation. With the help of a very accomplished gospel choir, he delivers his own idiosyncratic sermons against the rampant consumerism that he believes is suburbanising New York city.
His aim, he says, is to mobilise people to "attain a state of exalted embarrassment" about what consumerism is doing to the world around them and, hopefully, to do something about it.
The past week held mixed fortunes. On Tuesday a "sneaker riot" broke out on the Lower East Side of Manhattan after shoppers camped out for up to 48 hours to buy limited edition Nike Pigeon Dunk skateboarding trainers.
Only 150 pairs were manufactured and only 20 were on sale in New York. When some people began pushing in the queue, the police were called.
"That's cultish consumerism right there," says Reverend Billy. "But there is hope. We are the diffi-cult."
On Thursday came better news. Efforts by Wal-Mart to penetrate the New York market by opening a 132,000 sq ft (12,260 sq metre) store in Queens was shelved after popular opposition forced the developer to bow out.
"Alleluia," says Reverend Billy. "The devil will not be coming to Queens."
He began his crusade in the late 1990s, when the then mayor Rudolph Giuliani's transformation of the city was in full throttle. "There was a cultural cleansing of the city," says Reverend Billy, referring specifically to the area around Times Square.
"They didn't just get rid of sex workers. They got rid of interesting people - poor people; people of colour. They made it safe for Disney."
As an actor he saw the changes most markedly in the theatre. "There used to be 200 original shows on Broadway every year. Now they just turn big-budget movies like the Lion King on stage. Only 12% of New Yorkers go to Broadway shows now. Unless you work there, no one from New York goes to Times Square any more. It's just for tourists."
The best theatre on Broadway, he thought at the time, was taking place on the street, where store-front preachers were trying to save the prostitutes, beggars and drug addicts who had strayed.
He decided to adopt their style, but change the substance of their message. What emerged was a spirited spoof of televangelism. Reverend Billy has been known to exorcise Starbucks cash registers, for which he spent three days in a Los Angeles jail during election week.
Wal-Mart's setback may have slowed down the pace of suburbanisation in New York, says his partner and manager, Savitra D. But she admits that most of Manhattan already looks like a glitzy version of anywhere else in the US and, thanks to initiatives such as the Olympic bid, the rest of the city may soon follow suit.
"It's like a logo epidemic," she says. "What used to make New York great was that you were constantly pushed up against people who you would never otherwise interact with, and things would happen." But as public space gives way to corporate-owned space, she says, the chances of those chance happenings become increasingly rare. "There are no real neighbourhoods in most of Manhattan any more,"
Or, as Reverend Billy puts it: "I'm drowning in a sea of irrelevant details."
His sermons in New York take place monthly and are getting bigger each time. Increasingly, however, he likes to take them on the road. He has preached in England and Germany He delivered one in the Houston cafeteria of Halliburton, the energy and defence group once headed by the US vice-president, Dick Cheney.
"There were these big white people eating big barbecue sandwiches," he says. "At first they thought I was a regular right-wing preacher. But then I started telling them to quit their jobs and divest." He told them Halliburton was the devil.
He has yet to take his show into most of the South. Ms D fears he might be killed. "It's just a very different scene down there and we have to be careful," she says.
Mr Talen knows of what he speaks. He was raised by fundamentalist rightwing Christians; Ms D's father is a conservative Muslim. "There are a lot of preachers' kids in the choir," says Mr Talen, who would not describe himself as religious. "Half of the church is in recovery."