Religion will be a non-event in Australia within two generations according to the head of the country's atheist foundation.

David Nicholls says we are now seeing the tip of the iceberg as more and more people declare themselves non-believers and free thinkers.

But he admits religion will always be present in Australia because of indoctrination and because some people "need fairy stories to survive".

"Within two generations, religion in Australia will be a non event," he said.

"[It] will always be here, there's always going to be a genetic and cultural indoctrination, enough to affect some people, some people need it, some people get comfort from it, some people need fairy stories to survive, but not as many as before."

His comments came ahead of the Global Atheism Convention which started on Friday in Melbourne.

The convention has ignited debate in Australian media this week - most notably on Monday night's Q and A program when well-known atheist Richard Dawkins faced-off against Cardinal George Pell.

The convention follows a global trend of celebrating atheism. About 4,000 are expected to attend the weekend's events as Mr Nicholls says non-believers now realise they need to make themselves heard.

The latest census data suggests the number of atheists is increasing - from 17 per cent in 1996 to 19 per cent in 2006. While Christianity remains the dominant religion at 64 per cent of the population, it is on the decline.

"There's now a growing awareness that religion is affecting people through politics and social stigma and they're starting to work out that the only way we can alter the status quo is by making ourselves visible," Mr Nicholls said.

'Tortured forever in hell'

He says governments around the world are too influenced by religion, but religion's biggest failing is its impact on children.

"This is probably the worst thing that religion does - it threatens children that if they don't believe they're going to be tortured forever in hell and if they do believe it they'll be eternally blissful in heaven," he said.

Mr Nicholls says fears that humanity's moral code would disappear with religion are totally baseless because morality is innate in our nature.

"The moral code of most religion is highly suspect and women should be the first to recognise that," he said.

"Morality has grown through consensus of not wanting to have something done to you, not doing anything to others that you wouldn't want done to you.

"The golden rule is not something that religion has invented, it's just a matter of what happened with humanity as it came down from the trees and ventured out into the plains and became us."

But critics of atheism say the movement has been bred out of today's "crisis in morality".

The ABC's Religious and Ethics editor and former Uniting Church minister, Scott Stephens, says as social and political debate decays, people feel the need to have some kind of identity.

This brand of atheism which he says is increasingly bawdy, salacious and juvenile, is becoming popular.

"It ends up being a way of glossing or sexing up what is most basically a form of wellbeingism," he said.

The history of ideas

Mr Stephens says as aspects of Western democratic life run aground people will also turn back to religion.

"It's not that people are returning to religion as a kind of long-lost security - there's nothing nostalgic about this - but what increasing numbers of atheists, philosophers, serious public intellectuals are recognising is that there is a not just depth, but a kind of fundamental questioning and thinking, there are a series of traditional intellectual and moral resources that are bound up with Christianity, with Judaism, with Islam," he said.

But Mr Stephens agrees with atheists that religion has no place in politics or education.

"The church is not and mustn't be a lobby group. The only place for social and political activity that the church has open to it is the speaking into and the attempt to persuade in the context of public and social debate," he said.

"Secondly, I've been very critical of the way religious education in particular is being conducted here ... the forms of relatively silly and cartoon-like religion that are often championed within religious education, it's not doing the children any good and if I may speak as a person of faith, it's not doing people of faith any good either."

But on the other hand Mr Stephens says David Nicholls' comparison of religious belief to believing in fairies is "outright stupid".

He says religion is bound in the history of philosophy and the history of "ideas themselves".

"What we're talking about here - whether it be Christianity, Judaism or Islam - are ancient traditions that have been in relentless rigorous dialogue with every philosophical tradition, every moral movement, every literary tradition. These are traditions that exercise rigorous forms of self-criticism, of development," he said.

He says instead of opposing each other, atheists and religious minds must come together to wage war on society's moral crisis.

"An alliance between atheists, humanists and those who belong to the Catholic and Orthodox tradition to begin fighting for what is best and most defendable and most virtuous within western civilisation," he said.

"I think it's that kind of alliance against a common foe - which is this massive social and moral decline that it seems to me we're seeing everywhere - that's where the future really lies, not in the glorified cock fight that we saw on Q and A on Monday night."