An atheist church minister could be defrocked after The United Church of Canada (UCC) dismissed her appeal against a review into her effectiveness.

A judicial committee has rejected an appeal by Rev Gretta Vosper to stop the planned review of her fitness to lead her congregation.

Vosper, 57, leads West Hill United Church in Toronto and has been open about the fact that she doesn't believe in God. She has both blogged and spoken publicly about it, and in 2008 published a book titled: With or Without God: Why the way we live is more important than what we believe.

Although she told her church in 2001 that she was an atheist, and made it known more publicly in 2004, the Toronto Conference of the UCC only called for a review of her ministry last year.

Vosper appealed the review, but the committee dismissed it this week, saying: "After fully and thoroughly considering all submissions by the appellant and respondent, the executive of the judicial committee decided that the appeal did not meet the grounds for an appeal."

Vosper said she was "incredibly disappointed" with the decision.

"Every pastoral relationship in the United Church of Canada will be affected by this ruling," she told The Canadian Press.

"Now a court of the church can intervene in that relationship – and terminate it."

Having led her congregation since 1997 without intervention, Vosper was first investigated after writing an open letter to the UCC's spiritual leader following the Charlie Hebdo massacre in Paris. She said that belief in God can motivate bad actions.

The review was first initiated by Nora Sanders, the general secretary of the Church's general council, in May 2015, in order to determine whether Vosper was being faithful to her ordination vows. These include affirming a belief in "God: Father, Son, and Holy Spirit".

Vosper's congregation is firmly in support of their minister. The church's chairman said he was "disturbed" by the process.

"Everything up to now has been adversarial, closed, no transparency. Did they look at the documents? What were the merits?" he said.

"There is strong resolve to carry on because everyone keeps saying this is a special place, we cannot let this place go."

A date has not been set for the review.