About 31 per cent of students at independent schools are categorised as having no religion, up from 24 per cent in 2011, and 14 per cent of students at Catholic schools did not have a religion, up from 10 per cent in 2011. The change reflects a drift to secularism in the wider population. About 30 per cent of people reported “no religion” in the 2016 census, up from 22 per cent five years earlier. The trend is most marked with the younger population, with 39 per cent of those aged 18 to 34 reporting no religion. Just over one in two Australians of any age identified as Christian, with Catholicism and Anglicanism the two biggest denominations. "Schools may need to think about the implications of the slow but steady rise of secularism, and the ways this may affect their approach to religious education and how they market their schools," the Independent Schools Council of Australia states in its analysis. Matt Beard, a fellow at the Ethics Centre, said the rise in non-religious students wouldn't necessarily affect the approach schools take to education.

“If you found out students aren't reading literature, you wouldn't stop teaching novels," Dr Beard said. "But it may provide a catalyst for having a discussion around whether religious education is a critical analysis of faiths and their place in society or teaching the tenets of particular religions." Social researcher Rebecca Huntley said the Baby Boomers kickstarted the rise in no religion, but also a changed relationship with the church even for those who identify with a religion. "Children get their religious direction and affiliation from their parents and with each generation since the Baby Boomers we've seen not just a decline in people identifying on census documents as belonging to a particular religion but also a decline in behaviour associated with religion," Dr Huntley said. "You might put that you're Catholic on the census form but that does not necessarily mean that you go to church every Sunday and do the other things the church might tell you to do." Dr Huntley added that, anecdotally, she'd observed parents "suddenly declaring for a religion and doing things like baptizing their child to give them more school choice".

The number of students describing themselves as having no religion increased 68 per cent at Catholic schools, 48 per cent at independent schools and 41 per cent at government schools. The next biggest increase was in students who said they were Christian, with a 59 per cent increase in Catholic schools, a 15 per cent rise in private schools and a 27 per cent rise in government schools. Students professing to Islam also grew by 19 per cent in Catholic schools, 41 per cent at independent schools and 36 per cent at government schools. Greg Whitby, executive director of the Catholic Education Diocese of Parramatta, which oversees 80 schools, said the diocese "recognises things are changing" and caters to students with different levels of understanding in faith-based lessons. "Though Catholic students have enrolment priority, we welcome other community members who wish to join our caring learning communities," Mr Whitby said.