The shifting of the “no religion” response to the top of the list of responses on the Census form was a major reason for a bump in that share of Australians from 22 per cent of the population in 2011 to 30 per cent in 2016.
The share of Christians actually dropped by a greater amount - 61 to 52 per cent over the same time frame.

A break down of emerging religions (ABS) Source: ABS
The group of Catholics declined from 25 to 23 per cent, Anglicans from 17 to 13 per cent and each of the minor Christian denominations also recorded reductions.
But non-Christian religions actually grew in their share of the population, from 7 to 8 per cent due to small increases across Islam, Hinduism and Sikhism.