Inevitably, the words Moderator of the General Assembly of the Church of Scotland conjure up a dark-clad image of dog-collared rectitude. Even after the first woman was appointed to the post three years ago, it is hard to move away from the assumption that the incumbent will be a middle-aged male minister.

Sheilagh Kesting is a minister and, at 53, has spent her life in the service of the Kirk. As the first woman minister to be appointed to the post (Alison Elliot was an elder), she has already said that she hopes to be an inspiration to women in churches throughout the world, including those which ban women from their ministry. That should not be dismissed as a pious hope. For all her cheerful, understated demeanour, the Rev Sheilagh Kesting is a quiet rebel.

Even so, she admits to being apprehensive in advance of her year in the limelight: "Inevitably there are high expectations and you just hope that you are going to be able to fulfil them." In her case these are heightened by the fact that she is the first woman minister to be Moderator, and her consciousness that this is both a privilege and a burden.

For the past 14 years she has been secretary of the Church's ecumenical relations committee, and the drive to cement the common bonds between different Christian denominations, which has been the most significant feature of her ministry, will be equally to the fore. The seeds were sown in her early childhood in Stornoway, where she was born and lived until going to university in Edinburgh.

It had what she calls "an interesting influence" on her life. "I was brought up in the Church and became a Sunday School teacher, but from an early age I became aware of the degree of tension which existed between the different churches on the island - not just between Protestant and Catholic, although that was a very real one - but also between the different Presbyterian churches. All of that didn't seem to me to make sense, because when you meet people from other Churches they seem fine people."

The denominational divisions run particularly deep in the islands, but her parents taught her what she calls "a more open acceptance within Christianity."

Once ordained, sometimes simply as a result of seizing an opportunity, it has been a feature wherever she has worked. In her first charge in Lanarkshire, she first met west of Scotland sectarianism face to face.

"Even then, in 1980, it was at a time when people were beginning to realise that this is not how things should be. In my time there we began to seek opportunities to do things together with the Catholic church down the road." From today's perspective, joint worship during the week of prayer for Christian unity or the Church of Scotland minister attending the anniversary celebration of the Catholic church building hardly seems revolutionary.

For Kesting, at the time, there was a frisson of storming the barricades. "There was an excitement about it, because it was going into what had been forbidden territory. There was a hunger to find out how other people did things, and we began to discover that in fact we share a lot more than everyone had believed."

She built further on that experience in her next charge, St Andrew's High Church in Musselburgh. When she arrived in 1986, it was a newly united church and perhaps particularly open to fresh thinking. That, combined with the fact that she arrived at the same time as a young priest as the new curate at the neighbouring Catholic church, produced an opportunity she quickly seized.

Together with the priest, she set up a group of the Not Strangers but Pilgrims programme, in which people get together in small groups and share their faith. In Musselburgh it also involved the Scottish Episcopal Church, the Congregational Church and the Seamen's Mission. Not Strangers but Pilgrims was to change the ecumenical process in Scotland. As Kesting says: "It led to the total reshaping of the way we work ecumenically, not just in Scotland, but in Britain and Ireland. We set up Acts - Action for Churches Together in Scotland - and at that point, the Roman Catholic Church was able to come in as a full member.

In turn, her seven years in Musselburgh shaped her future in the Kirk. "It's the place where I matured and realised the importance of working with other parishes and faiths. I had a tremendous congregation who were very active in working together, and all of my subsequent ecumenical work has stemmed from my time at St Andrew's High," she says.

Immediately after that she became secretary to the committee on ecumenical relations. It was her dream job. She remembers that when she first met her predecessor in the job, she thought: "If there is any job in the Church of Scotland I really would like, that's it." When he retired, it seemed the right thing to apply for it.

It's an illustration of her gentle determination. Nevertheless, after 14 office-based years, she says what she misses is "the privilege of a parish minister working very closely with people as a friend, as a pastor. One of the main privileges of being a parish minister is being able to build up relationships with a congregation." A renewed contact with people at local level is one thing she is particularly looking forward to in the year ahead.

before that, however, she will preside over a historic ecumenical gesture. It is now all but certain that one of her duties next week will be the unprecedented one of welcoming the convener of the Free Church of Scotland's ecumenical committee to address the Church of Scotland's assembly. In a historic step, the general assemblies of both churches will be asked to agree a joint statement which recognises "the scandal of the divisions in our Presbyterian Church family". It will be a thrill for Kesting, who was secretary of the group which produced the statement.

"I think it is a tremendous thing. I don't think any of us guessed that we would be able to do such a thing, but we have been meeting for a couple of years and it became clear that there were areas where we could say we have common ground. There are still huge potential tensions between us, but at least we are talking and that is a positive thing. We have been able to say something in common and the hope is that our respective conveners of ecumenical relations will address each other's assemblies. It now looks as if it will happen this year, which I am thrilled about."

Nevertheless, she knows how pernicious the long, bitter legacy of the Disruption of 1843 remains. Any re-unification of the two churches would be "over the horizon," she says.

The process will continue and she says the group hopes that they can discover more common ground and there will be further movement.

The issue of ministers being able to bless the civil partnerships of same-sex couples threatens to be divisive, but as moderator Kesting says her own view is "irrelevant." The proposal from last year's assembly that ministers who carry out blessings on same-sex couples should not be disciplined has been rejected by the presbyteries. As a result, they revert to the status quo, which means that ministers make their own decision on whether to carry out blessings ceremonies for gay couples, but those who do may be at risk of being disciplined by their presbyteries. That report, however, will be merely noted.

The thorny issue may or may not come up in the wider context of the discussion on human sexuality. The Moderator Designate is hoping that debate will be conducted "with respect". She says: "The report says there is a range of viewpoints, but it is not asking the assembly to come to a decision on any one of these, but to go away, discuss and listen."

In moderatorial tradition she hopes to carry out two foreign visits. The first will be to Australia and New Zealand, where after meeting delegates to ecumenical gatherings, she is keen to see how they operate. The Presbyterian churches in the southern part of the South Pacific archipelago of Vanuatu, which were founded by Scottish missionaries in the nineteenth century, recently wrote "out of the blue" to the Church of Scotland saying they would like to have fraternal relations, so she will take the opportunity to extend her journey to the islands. "It will be wonderful to rediscover what this church is about after all these years."

Plans for a visit to Syria and Lebanon are more tentative because of the political situation there. Again, her impetus is the ecumenical context. "In the Middle East, churches have to work ecumenically and it is their Christian identity that comes first, before their denominational identity because they are such a beleaguered community. The other reason is to go and show solidarity with Christians who feel forgotten."

She assumes her high-profile role at a time when church membership is reported to be at an all-time low of 504,363, but instinctively looks beyond mere statistics.

"We can get too anxious about numbers. If we remind ourselves that the church is about the gospel and focus on what that means, I think the church becomes more relevant and therefore, perhaps, the numbers will go up.

At the end of the day, it is not the numbers that count - it is the quality of our witness and how we care for people that really matters," she says.