David Giuliano, the church’s leader from 2006 to 2009, compared Ms. Vosper to an Amazon manager who doesn’t believe in online shopping. “I suppose someone could have the skills to do it,” he said. “But why would she want to?”

Ms. Vosper has felt she belongs in the church since she was a child, growing up in a rambling house in the university town of Kingston, Ontario, with a view of one of its stony steeples from her bedroom window. The family would all bundle up and go there on Sundays, and both her parents — an engineer and a nurse — were active members.

Although as a child, she claimed Jesus had taught her to skate, she never considered herself a devotee. Instead, she says she has always understood God obliquely, as love.

After graduating from college with an arts degree and in search of adventure, Ms. Vosper moved to the far north of Canada, where she was married and had a daughter. After her marriage broke down, she returned to Kingston as a single mother and enrolled in divinity school.

“I wanted to learn how to make the world a better place through it,” said Ms. Vosper, who is sprightly, with short salt-and-pepper hair, chunky glasses and a penchant for bubbling over with language.

By then, the United Church of Canada was propelled more by social justice than theology, according to Kevin Flatt, author of “After Evangelicalism: The 60s and the United Church.” The first church to ordain transgender ministers, its leadership supported abortion and same-sex union before either became legal in Canada.

Divinity school cemented her metaphorical views of God, Ms. Vosper says. But once she began preaching, she realized many congregants thought she was talking about an all-knowing, all-seeing spirit who answered prayers and called some to heaven and others to hell.