The number of Canberrans with 'no religion' rose about 13 per cent in the past decade, with falling numbers of Catholics and Anglicans, and the ACT recorded as the second least-religious jurisdiction in Australia.
Data from last year's census released on Tuesday showed some 36.2 per cent of ACT residents reporting 'no religion' on the national head count, rising from 23.4 per cent in 2006.
The falling numbers of ACT residents engaged in organised religion is part of a wider national and global trend towards secularism, particularly in western nations, with the data showing the biggest falls in Canberra were among Catholics and Anglicans.
While 22.3 per cent of the territory's residents self-reported as Catholics and 10.8 per cent were Anglicans in 2016, those figures fell four per cent each since 2011, and were down from 28 per cent and 16.7 per cent, respectively, in the 2006 census.
ANU's School of Demography's associate professor Ann Evans said it was part of a wider trend of people citing no religion, but a change in ABS forms in 2016 - moving "no religion" from the bottom of the list to the top - could have also been a factor.
"One of the things that stood out for me was that the ACT was the second-least religious place in Australia, only Tasmania have a higher proportion of people reporting having 'no religion'," she said.
"It's part of the nature of a changing society, across Australia, there had been an overall strong decline in religion by age, so those who were religious are getting older and growing numbers of young people aren't following a religion."
Concerned Catholics Canberra-Goulburn chairman and ANU emeritus professor in politics John Warhurst agreed the decline in followers of organised religions was part of a global trend.
But he said part of that may have been affected by the Royal Commission into Institutional Responses to Child Sexual Abuse - the revelations of which have had deep impact in both the Catholic and Anglican churches.
"It's probably only accelerating an existing trend, so I wouldn't want to overestimate the impact the Royal Commission has had, compared to just increasing secularisation of western society," he said.
But Prof Warhurst said he believed the change was also part of a wider loss of faith in the institutions of both religion and politics.
"It's hard to say the extent of it, but rejection of religious organisations seem to be a part of the wider rejection of the mainstream and the establishment," he said.
"It's a complex relationship, but I do think there's a connection between the two."