The number of Americans belonging to a place of worship has fallen to below the majority for the first time since 1999. 

A new study by US company Gallup has revealed that in 2020, 47 per cent of US adults belonged to a church, synagogue, or mosque down from 50 per cent in 2018 and 70 per cent in 1999. 

The Washington, D.C.-based analytics and advisory company has been recording church membership for decades, asking US adults for the first time in 1937 when attendance was 73 per cent. 

The study argues there are two main reasons behind the decline: age and a lack of religious affiliation in the country. 

Over the last two years, the number of people who do not identify with any faith has risen from eight per cent in 1998-2000 to 21 per cent over the past three years. 

As for age, 66 per cent of those born before 1946, also known as traditionalists, belong to a church compared to 36 per cent of millennials. 

"The decline in church membership, then, appears largely tied to population change, with those in older generations who were likely to be church members being replaced in the U.S. adult population with people in younger generations who are less likely to belong.

"The change has become increasingly apparent in recent decades because millennials and Gen Z are further apart from traditionalists in their church membership rates", the study reads. 

The Catholic Church is the Christian denomination that has lost the most members, going from 76 per cent to 58 per cent. Protestants have also recorded a reduction, down from 73 per cent to 64 per cent in the last three years. 

The study is not particularly hopeful about a change in the negative trend. It argues that while the coronavirus pandemic could have possibly affected church membership during 2020, "continued decline in future decades seems inevitable, given the much lower levels of religiosity and church membership among younger versus older generations of adults". 

You can read the full study here.