In 2016, following the Charlie Hebdo shooting in Paris, her public statement that the belief in a supernatural God promoted hatred led the United Church of Canada to institute an official review of her suitability as a minister.

"[3] At age 17, she left high school a year early and enrolled at Mount Allison University to study literature, psychology and religion.

After earning her bachelor's degree, she briefly considered studying for ministry, but instead moved to the Northwest Territories, where she met and married Bill Ferguson, and had a daughter Hazel.

In 2011, Mardi Tindal, at the time United Church moderator, told a Toronto newspaper, "I celebrate Gretta and others like her who cause us to think more deeply about the nature of our faith.

[citation needed] In 2013, Vosper's beliefs moved from non-theism to atheism after she read about the plight of Bangladeshi bloggers who faced imprisonment and execution as blasphemers for questioning the existence of God.

[8] In an interview on CBC's The National on 26 March 2016, Vosper said that, in her estimation, "it would be at least upwards of 50% of the clergy in the United Church who don't believe in a theistic, supernatural, God".

[9] In November 2018, before the hearing could take place, Vosper and the United Church reached a settlement that allowed her to continue the work in her ministry, effectively ending the matter.

[10] Her lawyer, Julian Falconer, offered this comment: "Both parties took a long look at the cost-benefit at running a heresy trial and whether it was good for anyone (and) the results speak for themselves.