Just one year after Reverend Gretta Vosper was ordained by the United Church of Canada, taking a vow that God was the "Father, Son, and Holy Spirit," she stopped believing altogether.

It was 1994 and Vosper's young daughter Hazel's favorite teacher had just died from a brain tumor. Hazel was devastated, and furious at her mother who had recently taught her in Sunday school that if you prayed the right way, everyday, God would answer and he could heal. Clearly, it hadn't worked.

"I was so humiliated that I had actually said that and that Hazel felt her teacher hadn't gotten well because she hadn't prayed properly," Vosper, 57, recently told VICE News from her West Hill United Church congregation outside of Toronto. "When I heard that coming from her, I realized it was an abhorrent thing to suggest."

For the next few years, Vosper kept her doubts under wraps and went on to lead a large congregation. But a few years later, she cracked.

One Sunday in 2001, she stood up in front of her congregation, as usual. But instead of a normal sermon, she declared that she no longer believed in God. "Something came over me, and I took God apart," she recalled. "I said I didn't believe in an interventionist God, not a God that was a Being, I didn't believe in Supernatural powers, or Heaven or Hell...My understanding of God is more about relationships with oneself, the others, and the planet."

Much to her surprise, neither the congregation nor the church board were bothered by this. Many even confessed that they, too, had their doubts. And so they carried on, without God.

But now, the church's top brass say they've received too many complaints about Vosper and have launched an unprecedented investigation to determine whether she's fit to keep her job. Vosper is appealing the church's general secretary decree issued in May that lays out a plan to kick her out — also known as "defrocking." Both sides have lawyered up for an ecclesiastical court hearing slated for September.

It's a surprising turn of events, especially since the United Church is known for its progressive views about who can join the fold and who can lead — it was one of the first to welcome women and LGBTQ folks to the cloth. Vosper says she's going to fight to keep her job in the church not only because she loves the community, but also to stand up for her many colleagues she says also don't believe, but are too scared to admit it openly.

"I won't bow out. Because if I leave, that ruling stands and my colleagues are at risk. It's like I'd be running to safety, and everyone else gets blown up," she said.

Vosper's saga couldn't have come at a worse time for the United Church, which is already hemorrhaging devotees. Its membership has shrunk more than 60 percent since 1965, when it included more than one million. And across Canada, the number of people who say they aren't affiliated with any religion — known in academic circles as religious "nones" — has risen from 10 percent in 1985 to more than 25 percent today.

"Our numbers are at an all time low. Finances are at rock bottom. We're closing one church a week, on average. So there's a lot of stuff happening with institutional insecurity," said Vosper. But she says she's the church's biggest advocate and will do what it takes to keep her doors open.

It wasn't until 2013 that Vosper actually started calling herself an "atheist." At that time, there were four Bangladeshi bloggers who had been arrested for not believing in God. "I decided that as a mark of solidarity with those people who were being oppressed and denied their human rights, I would become an atheist alongside them," she said.

And by doing so, she thought it would encourage many other colleagues in the church who also do not believe in a theistic God to use that word. "But that hasn't really worked," she said. "I think that's because the word atheist is so packed with a lot of negative things. It's almost equated with being a satanist."

Vosper knows many might find the idea of an atheist minister confusing, even impossible.

After taking an early retirement from his role as lead minister with the Metropolitan United Church in London, Ontario, Bob Ripley realized he was an atheist, and went public with it in 2014. But unlike Vosper, he chose not to fight the church on it and gave up his status as a minister with the church. "I couldn't put the two together," Ripley told VICE News.

"People who no longer believe in a supernatural divinity, have every right to do so. They can and should form their own communities. But to do it under the umbrella of a Christian denomination, I just can't go there."

He added that Vosper's fight is not an issue of justice of inclusiveness. "I think the church has to give some definition to what it is, which is people who believe in a supernatural divinity. That's what gives it its substance," he said.

While Ripley and Vosper disagree that atheism and Christian ministry can be reconciled, they both told VICE News about a large group of "closeted clergy" within the United Church and beyond who struggle with or question their beliefs, but are petrified to speak about it openly.

Ripley and Vosper work with The Clergy Project, an anonymous online community for former and current clergy members who are doubting their faith, or no longer believe in God. Since it started in 2011 with 52 members, it has grown to more than 660 from congregations around the world. Through the Florida-based site, members can discuss their challenges, and even access grants to help them transition into secular life.

Terry Plank, president of The Clergy Project's board of directors who left his ministry in California 35 years ago, told VICE News it can be daunting for religious leaders to come clean once they stop believing. Many could lose their job, their family, and be shunned by the only community they know.

Plank said that there has likely always been non-believing members of the clergy, and it's not necessarily a new phenomenon. But things are changing because there are new tools that allow them to connect with each other for the first time. "This exposure of the underbelly of the church, as I like to call it, is so much greater now because of the internet, so now a pastor or religious leader struggling with this is no longer isolated, there's a whole community out there."

He added that there seems to be a strong trend toward secular congregational life, and points to newly formed "atheist churches" such as the Sunday Assembly, which was started in 2013 by two comedians from the UK.

Vosper sees her fight as the latest battle for full equality in the United Church. She is hopeful she will be successful, like the women and LGTBQ clergy before her who had to overcome barriers to be accepted.

"I'm betting on the United Church of Canada being the first denomination to have the courage to step beyond doctrinal boundaries and say we are a church that is about love, compassion, and justice," she said. "I believe the United Church has the chutzpah to do this."