The Church of Scotland will debate today whether gay ministers should be ordained.
The General Assembly will decide whether to retain a ban on ordaining gay ministers until a report is published next year.
Alternatively, they may decide to lift the ban now with another report to be published in two years’ time.
The church was threatened by a schism two years ago when an openly gay man in a relationship was ordained.
The controversy began when Reverend Scott Rennie was appointed as minister of Queen’s Cross Church, Aberdeen. His ordination was opposed by many in the church because he is openly gay and lives with his partner.
However, his congregation voted overwhelmingly for him to become their minister.
Following this, the church placed a moratorium on gay clergy to last until this year.
Research has found that one in five church members have said they will leave if out gay ministers are permitted.
One in ten said they will leave if the ban continues.
Dr Bill Naphy, an expert in the history of sexuality and Calvinism from Aberdeen University told the BBC’s Politics Show: “I think the Kirk is likely to take a very cautious approach.
“I think if they allow the ordination of gay ministers there will probably be whole congregations that leave.
“I think it’s less likely that whole congregations will leave if it goes the other way. It is more likely that individuals will walk away.
“Either way the vote goes there will be people and congregations who are likely to leave.”
He added: “The very fact that the Kirk has spent two years debating an issue that relates to handful of verses in the Bible must seem a very peculiar thing for the Kirk to spend its time on.
“In actual fact the Bible doesn’t say a great deal about sexuality at all.”