"Science and religion are incompatible," argues biologist, Jerry A. Coyne, in his 2015 book, Faith Versus Fact.

"They have different methods for getting knowledge about reality, have different ways of assessing the reliability of that knowledge, and, in the end, arrive at conflicting conclusions about the universe."

Coyne believes science and religion are diametrically opposed, locked in an irreconcilable "war between rationality and superstition".

For others, however, science and faith go hand in hand.

Some have even left a career in science to answer a call from God.

Benji Callen, Minister at Burnside City Uniting Church in Adelaide, always wanted to be a scientist a geneticist, like his dad.

"Where some people imagined a trophy for a footy premiership, I would imagine a Nobel Prize sitting on my bookshelf," he says.

"I always loved the scientific world. I loved imagining that I could understand something about the universe that no one else had understood before."

Reverend Callen studied science at the University of Adelaide before completing honours in biochemistry. He then spent five years working on a PhD in molecular biosciences.

He was working in a nanotechnology lab at the University of Liverpool in the UK when he received news that his PhD had been accepted.

His five years of hard work had paid off he'd done well and "got a good paper".

His wife, dad, and colleagues at the lab were all elated on his behalf.

But, despite his success, Reverend Callen's heart was elsewhere.

He realised it wasn't his burgeoning science career that most animated him.

Instead, his mind was drawn to his recent discussion with two other members of his church youth group about the meaning of life.

"I thought, 'My science career is going really well why am I far more excited about this conversation?'"

Reverend Callen had started attending church in his late teens and worked in youth ministry at his church in Australia. In Liverpool, he'd joined a Methodist church whose minister also had a PhD biochemistry. "The minister before him had a PhD in astrophysics," the reverend notes.

One of Reverend Callen's lab colleagues also volunteered at a church youth group. "He was happy being a science educator and doing ministry on the side. It was good to know that was possible."

But Reverend Callen realised he was different. While he "enjoyed the intellectual rigour and creativity" of working in science, he "always had this sense that something wasn't quite right".

So, when he and his pregnant wife returned to Australia, he applied for a role as youth pastor at his old church.

He got the job and started studying for a Bachelor of Theology in 2005.

The unease he had felt throughout his lab career vanished.

"I did feel a little sense of sadness or loss," he acknowledges.

"As soon as you step out of science, particularly research science it's really hard to get back into the game. I knew that there was no turning back."

Reverend Callen is now the minister at Adelaide's Burnside City Church, after spending eight years as a minister in the fishing town of Port Lincoln.

"People talk about it being one of the hardest jobs around, and I'd agree with that," he says. "I enjoy the huge variety no one day is ever the same."

Ann Edwards, Priest-in-Charge at St Mark's Anglican Church at The Gap, remembers always having a sense of faith.

As a child, her grandmother would take her to church.

In the days before women's ordination, she used to joke she would become the first female priest in the Anglican church.

"That idea was always there," she says. "I had a sense of vocation and call even from my early teens."

When a wristinjury prevented Reverend Edwards from pursuing the clarinet after school, she chose a new career path almost at random: speech pathology.

"I fell in love with the science of it," she says. "I loved anatomy and physiology and the psychology of it how brains worked. It captivated me."

Reverend Edwards established a rewarding career working with people with swallowing disorders caused by stroke and neurological disease.

"I had no plans to go anywhere," she says.

Despite the satisfaction she derived from speech pathology, Reverend Edwards still felt a call to God.

"I had this real sense of pull into ordained ministry," she says.

In 2014, she followed the call and began training as a priest.

She felt the skillsets she developed in her life as a speech pathologist, manager and researcher would be of great use in the practical business of running a church, particularly in improving disability inclusion, an issue she was passionate about and the focus of her theology thesis.

At the same time Reverend Edwards was embarking on her theology studies, she took up an academic role in speech pathology at the Australian Catholic University. She now wore "two hats" one "as a researcher in speech pathology, and as a researcher in church access."

As a minister, Reverend Edwards finds the same satisfaction from building relationships that she did in her clinical work.

"All those things that I loved about speech pathology are still here I'm still seeing people succeed, I'm still mentoring people," she says.

Reverend Edwards believes her scientific training is good preparation for the challenge of adapting ministry to a digital world, a prospect she finds exciting rather than daunting.

She sees no conflict between her "absolute belief [in] and love of science" and her faith. "My faith is informed by science," she says.

At Christmas, she delivered a sermon on the religious and scientific conceptions of creation and "how beautifully the two work together it's almost like a tapestry".

"The [Bible] stories have so much depth," she says. "They still speak truth if we don't hold them literally, and we hold them as they were meant to be."

She doesn't feel that her scientific background makes her an outlier in the religious world she now occupies.

"If you look at my community it's full of doctors and nurses and social workers," she says.

"There are more PhDs than you can poke a stick at here I'm not unusual at all."

Like Reverend Edwards, Reverend Callen sees science and faith as "complementary" not contradictory.

"Science does a great job of the 'how' of life, answering those 'how' questions 'How do cells work? How do stars work? How does gravity work?' but it does a pretty rubbish job at the 'why' questions 'Why are we here? Why do we have hope? Why do we love? Why do we hate?'"

He believes Christianity offers answers to those philosophical 'why' questions.

Both ministers talk about the "awe and wonder" they find in equal measure in faith and science.

Reverend Edwards finds affirmation of her faith in the natural world. Observing a "tawny frogmouth standing so still that you couldn't even see it in the tree that was a thing of awe and wonder for me," she says.

Reverend Callen says, "To be a good scientist, you need to have a sense of awe and wonder and curiosity about the universe."

He believes worship requires the same qualities. "For me, going into the lab and discovering something new about the universe was my meditation and prayer. It was my awe and wonder."

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Leap of faith: The people who left science to answer a call from God - ABC News