TASMANIA is leading the nation in people identifying as having no religion, statistics show.

At the last census, Tasmania and the ACT had the highest rates of people reporting no religion at 29 per cent.

New South Wales had the lowest number at 18 per cent.

Catholic Archbishop Julian Porteous says society is in a state of flux.

"There are many factors that are changing the demographic make-up of our society," Archbishop Porteous said.

According to the 2011 census, the largest single religious denomination in Australia is the Catholic Church which represents 25.3 per cent of the total population.

"The census also revealed that more than 13 million people in Australia identify as being Christian, demonstrating that Australia is principally a Christian nation," he said.

In Tasmania, Christians make up 59.6 per cent of the population.

The number of people reporting no religion has increased steadily, according to the Australian Social Trends report released by the Australian Bureau of Statistics yesterday.

ABS director of social and progress reporting Fiona Dowsley said about half the people reporting no religion were under 30 and people who were highly educated were also more likely to report no religion.

"Rates of reporting no religion have been steadily rising, and Australia is not alone rates are also rising for countries like New Zealand, England and Wales, Canada, the US and Ireland," Ms Dowsley said.

UTAS Atheist member and Launceston Skeptics president Jin-oh Choi said the stats came as no surprise.

"Most people are starting to realise religion doesn't offer them too much and as they see they only have one opportunity in life rather than waste it on religion it's important to cherish the time we've got," Mr Choi said.

Divisive legislation on topics such as euthanasia and same-sex marriage also played a role, he said.

zara.dawtrey@news.com.au