The Church of Scotland will this weekend make a final, historic vote on the ordination of ministers in same-sex civil partnerships.

The General Assembly opened this morning with the installation of a new moderator, Rev Dr Angus Morrison. One of his first tasks in his new role will be to chair a vote that will be the final say on proposed legislation that could lead to the ordination of ministers with a civil partner.

If it is approved, then a further vote on Thursday will see the Assembly consider the ordination of clergy in same-sex marriages.

Ahead of today's vote, Morrison said that even in the midst of difficult decisions, "We are all one family".

The debate has been ongoing for some time in the Kirk. In 2013, the Assembly concluded that the Church could not condone same-sex marriages or civil partnerships, but commissioners voted in favour of a proposal that would allow individual congregations to 'opt out' of the Church's official policy on homosexuality, and could choose to employ a gay minister should a vacancy arise.

Then in May last year, the Assembly voted overwhelmingly in favour of a proposal that could lead to the ordination of actively gay ministers, with a majority of 369 to 189. Draft legislation was passed to the 46 individual Presbyteries to debate, and the majority voted in favour of the change.

However, it has been a divisive issue for many. According to the Kirk, 21 of 806 ministers have left the Church as a result of the tensions. Some congregations have also opted to leave; choosing instead to join the Free Church, which has a firm stance against homosexual clergy.

David Robertson, minister of a free church in Dundee and director of the Solas Centre for Public Christianity, has previously said that confusion surrounding the official line on homosexuality has made a "laughing stock" of the Church in Scotland.

However, Rev Scott Rennie, an openly gay minister who caused controversy in 2009 when he was appointed to Queen's Cross Church in Aberdeen – a Church of Scotland congregation – last year welcomed the move towards ordination of those in same-sex relationships.

He told Kalaidoscot: "The voting figures are hugely encouraging, and shows the Kirk is moving to a supportive and helpful understanding of modern families in all their shapes and sizes.

"All over Scotland, churches that offer people an opportunity to explore spirituality in a modern and open setting are growing. The Moderator has called on us to grow our congregations – this can only help."