The Church of England's general synod, meeting on 14 February, will consider changes that could fundamentally change the church.
It will be asked to start the process that could soon see women chosen as bishops for the first time in England.
It will again be debating whether to allow gay and lesbian Christians to work as priests.
And many synod members will want to pronounce on the forthcoming Royal wedding, though calls for an emergency debate have been rejected.
The forthcoming Royal wedding will be up for discussion
Their concern over the decision of Prince Charles and Camilla Parker Bowles to marry stems from his presumed future role as supreme governor of the Church of England, one of the monarch's traditional titles.
Leaving aside the prince's own matrimonial history, Mrs Parker Bowles, as a divorcee whose partner is still alive, is not eligible to remarry, according to the church's rules.
And although the couple plan a civil wedding, to be followed by a blessing by the Archbishop of Canterbury, Dr Rowan Williams, some synod members believe the marriage will leave Charles unfit to head the church.
A vociferous debate is likely on women bishops, accepted for years in many other parts of the worldwide Anglican communion, but restricted in England to serving only as priests.
Members will spend much of their three-day meeting discussing a working party report on the issue, and then debate whether to hold another debate in July on actually going ahead.
Christina Rees: 'Crunch time' for Rowan Williams
One synod member, Christina Rees, a religious commentator, told the BBC News website: "A minority of synod members don't even want to discuss the report, but I think it will be accepted.
"Then we'll have a messy few months till July, with those opposing the idea very busy - they may argue they should be able to opt out if we do get women bishops.
"But there's research showing 85% of ordinary church members are very happy with the idea. And only four out of 43 diocesan bishops oppose it, so I think it will go ahead in July."
Search for solutions
The synod will spend much of its last day debating the report of a group chaired by the Archbishop of Armagh, Dr Robin Eames, published last October.
The group was set up to try to resolve the increasingly bitter dispute within global Anglicanism following the consecration of a gay bishop in the US, and agreement on services to bless same-sex unions in Canada.
Another stage in that dispute will unfold when the world's Anglican primates (archbishops and other national church leaders) meet in Northern Ireland from 21 to 25 February to study Dr Eames' report.
Christina Rees said: "There's been no shift in position in the synod on the report. It will have the effect of being a warm-up show for the main event, the primates' meeting.
"But people will be watching Rowan Williams, who's faced with what to do in Ireland. This is a crunch time for him."
Other debates include terms of service for the clergy, including the possibility of ending the freehold which virtually guarantees many a job for life, and environmental problems.