Is Australia the least religious country?

Australia is described as being a secular country, so it's not surprising that Census data shows a high proportion of people claiming no religion.  In 2016, for the first time, those claiming no religion outnumbered the most common religion (Western Catholic).  In effect, "no religion" is the most common religion in Australia.  But how does this compare internationally?  Is Australia the least religious country?  Read on to find out.

Data on religion in Australia

In Australia, the only reliable source of data on religion is the Census.  A person's religion has been asked in every Census since 1911.  However only since 1971 is it possible to determine the number of people with no religion.  Prior to this, they were included with the not stated responses.  It remains the only optional question on the Australian Census form and frequently has a higher non-response rate.

The chart below shows the number and proportion of people in Australia claiming no religion over the period 1971-2016.  Except for a minor decline between 1996 and 2001, persons with no religion have grown steadily in size.  In 1971, there were around 855,700 persons with no religion, representing 6.7% of the population.  By 2016, the equivalent figures were just over 7 million persons, or 29.9% of the population.  In almost fifty years, we've gone from one in sixteen people with no religion, to almost one in three.

The size of the increase between 2011 and 2016 (46% in no religion responses) was higher than in previous years.  This may be due to a change to the Census form where "no religion" was put at the top of the response list.  There were also various campaigns encouraging people to answer "no religion" if they weren't religious.  But even with these changes, there's no denying the long term nature of the trend.  People aged under 45 are more likely to claim no religion compared to older people.  These factors, as well as the historic trend, combine to suggest that in 2021 there will be another increase in "no religion" responses.  

Data from other countries

Obtaining comparable data from other countries is challenging due to a combination of data collection methods, the type of question asked, cultural issues and the role of the state and the church.  In order to keep things simple, I've limited comparisons to other major English speaking countries.  

In New Zealand a similar question on religion is asked on their Census form, but there can be multiple answers.  Census data shows that in 2018, almost half of New Zealanders (48%) claimed no religion, up from 42% in 2013 and 35% in 2006.

A Census is held every ten years in the United Kingdom, and the 2011 Census showed that 25% of the population in England and Wales claimed no religion.  Scotland recorded a higher proportion (37%).  The Office of National Statistics is actively seeking ways to collect data through administrative sources rather than rely on the Census, but estimates for religion are only available for broad geographic regions.

Stats Canada did not include a religion question on the 2016 Census form, but it was collected in 2011 via the National Household Survey.  This showed that 24% of the population claimed no religion.  By somewhat of a comparison, the 2001 Canadian Census showed that 17% of the population claimed no religion. 

South Africa no longer ask a religion question on their Census form.  It was last collected in 2001 when 15% of the population claimed no religion - similar to the proportion recorded in Australia that same year.

The United States does not include a religion question on their Census form.  Instead, religion data is collected via the American Religious Identification Survey (ARIS).  However this has not been conducted since 2008, when 13.3% of the adult population claimed no religion.

Even with this small sample of other countries, it's clear that there are many ways in which religion data is (or isn't) collected, making comparisons difficult.  What's interesting though is that where time series data exists, it does show a trend towards more people claiming no religion.  This is most obvious in New Zealand, where around one-third of the population in 2006 claimed no religion, to almost one-half in 2018.

Summary

Since 1971 there has been a (mostly) steady increase in the number and proportion of Australians claiming no religion.  The increase was higher between 2011 and 2016, possibly due to a change in the listing of responses on the Census form, but it still continues the trend evident over many decades.  International comparisons are difficult as religion questions are not always included on Census forms, or it's collected via survey data.  It may be difficult to determine if Australia is the least religious country, but the Census data shows that we are becoming less religious over time.