Queen and Stevie Wonder instead of hymns; a science lecture instead of a sermon. Can church work without belief in God? Esther Addley joins 300 people who say it can

"I feel sorry for the church next door, waiting for their three people to trickle in," says Nick Julius, glancing at the small adjacent hall that will shortly be hosting its own gathering.

There are still 40 minutes before the Sunday Assembly, an atheist service run by two standup comedians, is due to begin, but a queue of eager congregants is already forming outside a grand but crumbling former church in Islington, north London, hands shoved deep into pockets against the cold.

Julius arrived an hour early, just to be sure of a place at the service, which is described by its organisers as "a godless congregation that meets … to hear great talks, sing songs and generally celebrate life". But why? "I came last time and really enjoyed it. It's got all the good things about church without the terrible dogma. I like the sense of community – and who doesn't enjoy a singsong?"

This is only the second time Sanderson Jones and Pippa Evans have hosted the monthly event (motto: live better, help often, wonder more), and they admit to being a little overwhelmed by the enthusiasm with which the event has already been greeted.

More than 200 people came to the first event; today there are perhaps 300, with several dozen more carrying on a parallel discussion in a local pub. Inside the nave of the deconsecrated church, volunteers have been bunching chairs closer together, adding extra benches and children's seats in every scrap of space. It is not a problem most vicars struggle with on a Sunday morning.

The Sunday Assembly's congregation. Photograph: Sarah Lee for the Guardian

Jones, a tall, bounding figure with a hairstyle and beard verging on the messianic, says the idea emerged from his comedy, where he encouraged those coming to his gigs to get to know one another, and they in turn pressed him for ways to stay in touch and even build small groups. There was clearly a thirst for community, he decided, and perhaps others felt, as he did, that words such as awe and transcendence shouldn't be the preserve only of religious people.

"I would go to a carol service or a friend's wedding, and there would be so much about it that I really liked – the togetherness, the rituals – but I just couldn't get past the God bit." Atheism has been caricatured as a cold, empty position, he says. "But for me, my not believing in God if anything makes my life more precious, knowing that we are here for such a tiny amount of time."

The Sunday Assembly may be godless, but a churchgoer who stumbled through the wrong door would find much they recognised.

The service opens with a song, led by Evans and an enthusiastic band at the front; instead of a hymn, however, it is "Don't Stop Me Now" by Queen ("We've chosen something that allows hamming it up to the max"). The service features a reading, a moment of reflective silence, even a collection to pay for the rental of the church, during which people are invited to turn in the pews and greet those sitting beside and behind them. The plan in future is to engage members in community-based good works.

There is also a sermon, of sorts, on the day's theme of "wonder", which sees Dr Harry Cliff, a particle physicist from Cambridge, talking about Dirac's equation predicting antimatter ("the most amazing theory in history") and the enormous statistical odds against the universe existing in the first place. The congregation then stands to sing Superstition by Stevie Wonder.

Might the early popularity of the Sunday Assembly hint at the start of something that could take off on a large scale? Andrew Copson, chief executive of the British Humanist Association, is sceptical, noting that a wave of atheist churches were formed in the late 19th and early 20th centuries, but petered out because people found other forms of social organisation that suited them better.

"I think it's an interesting development but it's something that's been tried many times before. What's probably different is that there's a strong entertainment element. It's an entertainment as well as a communal activity. It just happens to be on a Sunday morning."

David Robertson, director of the Solas Centre for Public Christianity and a Free Church of Scotland minister in Dundee, is also doubtful. "I can understand why the format of church would be very appealing," he says, "but I do think it's going to appeal only to one particular section of the community" – what he calls "a middle-class cultural elite".

"The church is focusing on following Jesus Christ, and that cuts across cultures and across communities," he adds.

Having been startled by the popularity of the event, Jones insists his thinking about expanding the assembly has stretched only so far as adding an additional service next month, to be held in the afternoon. But there are signs that the idea could bear replicating.

Neil Denham and a small group of friends have come from High Wycombe in Buckinghamshire, hoping for inspiration. "We were just looking for ideas, whether something like this could work outside London," he says. Their verdict? "Some of the things I thought really wouldn't work, like the singing, were really good. Normally I hate singing."

Churches do a lot of what they do "because it works", he notes, "Atheists make a mistake to look at church and throw it all out just because they don't believe in God."

• This article was amended on 4 February 2013. The original referred to David Robertson as a Church of Scotland minister rather than a Free Church of Scotland minister. This has been corrected.