Sanderson Jones, founder of 'Sunday Assembly'.

No dogma: Comedian Sanderson Jones, founder of the Sunday Assembly, leads the gathering of atheists at Redfern Town Hall. Photo: Dean Sewell

It's Sunday afternoon and hundreds of people sing, clap their hands and talk about the wonder of life.

But it's not a church. The revellers, led by British comedian Sanderson Jones, are at Redfern Town Hall to celebrate atheism.

It's the first Sydney gathering of the Sunday Assembly, a group that aims to have ''all the best bits'' of church - without religion.

Jones launched the assembly in London but says when he toured Australia as a comedian, he realised there was an appetite for the idea around the world.

''But I didn't think it would spread so quickly,'' he said.

As a social trends report by the Bureau of Statistics highlights, Australians are increasingly ditching religious dogma. Just under 4.8 million people, or 22 per cent of the population, said they had ''no religion'' on their census forms two years ago.

It is an accelerating trend. In 1911, Australia was unusual in giving its citizens an option of saying they had no religion on census forms. Then just 10,000 people did so, or 0.4 per cent of the population.

From 1971 onwards, the ABS notes, those reporting no religion has risen by about 4 percentage points a decade.

And the non-religious have some interesting things in common. The report shows nearly half of same-sex couples report no religion, more than twice the rate of the overall population. Women aged over 15 are less likely to have children if they have no religion and are half as likely to have four or more children as the religious.

And 31 per cent of those with a postgraduate degree reported no religion, compared with one in five people with a high school education. Those who studied creative arts and sciences at university were most likely to have no religion.

Sydney Atheists president Steve Marton said younger people became involved in atheism as greater access to information allowed them to question views.

''Young people today aren't as brainwashed as their forebears; they can look past the religious text and dogma and look on the internet,'' he said.

''Social media plays a big part. They don't have to be closet disbelievers any more.''

Monash University's Emeritus Professor Gary Bouma said choosing to identify with a religion or not only revealed so much.

''A lot of it is a rejection of institutions, a rejection of conformity,'' he said. ''These people might be very spiritual.''

Spirituality was on show in Redfern, as Jones urged the crowd to clap and stomp to feel the wonder of being alive.

But not everyone was convinced.

Dane Armour, 25, left the hall unsure whether he would be back.

''It wasn't what I expected,'' he said. ''I think I need to go again to wrap my head around it.''