Lucy Turnbull has revealed she didn’t step foot in a Catholic church for more than 20 years because of an experience at a mass in 1972.

The successful businesswoman – and Prime Minister Malcolm Turnbull’s wife – says the words of a priest at a mass in New South Wales caused her to walk away from the church.

During a service, the Irish Catholic priest denounced a local Catholic girl who had been dating a Protestant boy.

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After that moment in 1972, Mrs Turnbull did not go back into a Catholic church until the mid-1990s.

“That experience at a mass in Mittagong in 1972 is still crystal clear in my mind,” Mrs Turnbull told Fairfax Media.

Mr Turnbull converted to Catholicism after marrying Lucy in 1982. He was originally Presbyterian.

Symptomatic of a wider issue

Although Mrs Turnbull’s departure from her church was triggered by a specific event, it is also in line with the way Australia and the world has wavered from Catholic observance.

In 1971, Australian Census data showed there were 3.44 million Catholics in Australia, or 27 per cent of the population.

In 2011, the Census data showed 23.3 per cent of the population was Catholic.

Just 12 per cent of the Australian population registered as Catholic in the 2011 Census.

While the percentage number of Catholics in the population only slightly dropped, the number attending mass fell dramatically.

In 1996 there were 4.8 million Catholics in Australia, and 17.9 per cent of them regularly went to mass.

A Fairfax Media report showed the percentage dropped every five years to the latest figures in 2011, where only 12.2 per cent of Catholics went to mass.

From 1954, where 74 per cent of Catholics attended mass, that is a large tumble.

According to the World Christian Database, Australia is following a worldwide trend, with followers of Catholocism declining since 1970.

It is something Pope Francis said his religion must address.

“I would like all of us to ask ourselves today: are we still a Church capable of warming hearts?” he said.

“Today, we need a Church capable of walking at people’s side, of doing more than simply listening to them.

“At times we lose people because they don’t understand what we are saying, because we have forgotten the language of simplicity and import an intellectualism foreign to our people,” he said.

One fateful night in September

During the wide-ranging interview, Mrs Turnbull also spoke about what she was doing during her husband’s successful tilt at becoming Prime Minister in September.

Lucy Turnbull knew her husband had won the prime ministership due to his beaming face.

“I look after my grandson every second Monday – sometimes every Monday,” Mrs Turnbull said.

“It was one of my Jack [her grandson] Mondays and I was in Sydney fully focused on the task of looking after a two-year-old, which makes it very hard to listen to the news.”

Mr Turnbull phoned her prior question time and said she should try and fly to Canberra that afternoon.

She said she arrived between 6pm and 7pm.

“It wasn’t clear what time the leadership ballot was going to be,” she said.

“I was in Malcolm’s office while all that was getting determined and happening all around me for the last hour or two.

“There was a buzz. When he came back I could tell by the beam on his face that he’d won. I got a text as well – so I knew. It was an interesting transition from a normal kind of day to a very exceptional day.”

** An earlier version of this story said that 12.2 per cent of the population of Australia in 2011 was Catholic. The correct figure is 25.3 per cent.