A seismic shift will certainly occur on August 9, with the “No Religion” box being promoted to first option in answer to the question “What is the person’s religion?” – up from last place in every previous census.

Odds are being given by the betting agency that “No Religion” will now have the highest score and dethrone the Catholics as traditional winners. They topped the pool in the 2011 census with 25.3 per cent. Anglicans then followed with 17.1 per cent, the Uniting Church 5.0 per cent, Eastern Orthodox 2.6 per cent and Islam at 2.2 per cent.

Consistently buried at the end of the list was “No Religion”, which still ran second with 22.3 per cent. But in August this figure is predicted to rise to more that 40 per cent. There are several reason why.

The trend towards secularism in progressive nations has advanced rapidly over recent decades. Australia is fully expected to now record similar figures to these countries. England is 48 per cent religion-neutral; Scotland stands at 52 per cent; and New Zealanders are 42 per cent non-religious.

But the true numbers are even higher than these – over and above those who are proudly religion-neutral. A majority of the population is brought up in households where there is a traditional family religion but later in life, and for a variety of different reasons, they drift away from those traditions and practise no religion at all.

Research shows these “uncommitted” people still register their childhood religion at each census, through sheer force of habit. The term is to be “culturally religious”. Many are ambivalent but others adopt a secular or rationalist worldview, based on reason and philosophical ethics. They don’t consider themselves religious.

The Australian Bureau of Statistics (ABS) has made this census change to reflect similar amendments in other Western countries. It also brings the Religious Affiliation section into line with other questions in the census, where the first response is often “No, go to next question”. And having “No Religion” as first option also encourages a more considered response, rather than a reflex action to mark one’s past ‘family religion’.

Marking “No Religion” does not mean you are an atheist; it simply means one no longer practises a particular religion. There are many Muslims who also reject Islam and they have the freedom to “privately” nominate as secular.

In addition, the new ABS format may encourage those who mark Spaghetti Monster, Jedi and Santa Claus to think more seriously about their religious affiliation, or the fact they have none.

So why is the census important?

Each five-yearly census provides vital information for all three tiers of governments to plan for housing, schools, health and social services, transport, and for economic, business and community infrastructure.

The “Religious Affiliation” question is essential, too, as many of these services are run as private businesses by religious organisations – not as charitable works, but as commercial operations that pay no tax. Research estimates that figure to be above $20 billion annually, although precise data is unavailable. Historically, church institutions claim exemptions from tax (and lodging returns) under the provision of “advancing religion“.

This provision has never been challenged, and it’s essentially due to the highly skewed census results that have given all churches a position of privilege. The question was “what is the person’s religion“, which automatically assumed everyone had one. But that is now negated, with “No Religion” as first option.

In 2011 the total Christian tally was an inflated 61 per cent – and I’ve mention above how easy it was for “cultural Christians” to mark off their “family religion”. Churches have fed off this inequitable advantage for a century.

At federation, the population was said to be 98 per cent Christian – it was only in 1991 that “No Religion” was added to the census, as the last option. This still gave the churches considerable political influence to retain their dominant social position.

We have moved from a public education system that was “free, compulsory and secular” to a position today where 40 per cent of children attend private religious schools – now funded by taxpayers at $11 billion annually. Public education is in crisis.

Australia is constitutionally secular. A true “No Religion” figure in this census will reaffirm that secular status.

Those who framed the constitution were adamant that the nation needed a transparent separation of church and state, but in recent decades federal parliaments have become increasingly Christianised.

Social issues such as same-sex marriage and voluntary euthanasia (both supported by more than 70 per cent of a secular public) are consistently opposed by governments and churches. And no progress has been possible on limiting religious school expansion, the Chaplaincy Program, religious instruction (rather than ethics) in public schools, and even the persistence of daily prayers in parliament.

All these, and more, contravene the very essence of a “secular” society – they are religious practices that have long been abandoned in the more progressive nations of Europe and Scandinavia. Plain Reason – and many other secular and rationalists organisations – continues to campaign for a return to Australia’s secular roots.

ABS has now rectified the structural imbalance of the census and that will enable a more even playing field in the public debate over contemporary secular social policy.

While responding to this question on religion is not compulsory, people are encouraged to consider it seriously and to answer it honestly and sincerely.

Brian Morris is director of Adelaide-based rationalist organisation Plain Reason and author of the book Sacred to Secular.