IT’S a Wednesday morning in Sighthill, Glasgow, and St Rollox Church is buzzing. A second-hand shop selling everything from clothes, shoes and toys to domestic appliances and textiles is doing a roaring trade, while in another room 20 women are learning sewing and dressmaking skills.

Yesterday the church – a modern, Brutalist 1980s brick building – hosted a befriending cafe, a computer skills course, a fruit and veg stall and an advice service, and later today volunteers will teach English to refugees, asylum seekers and migrants who have settled here. The church also gives emergency crisis funding when it can, and provides basics such as food and heating to an increasing number of parishioners.

The people here today using and running the activities are a noticeably multicultural bunch from Africa, the Middle East and Asia, and, of course, Glasgow. Most are female and many of the locals are elderly. All, however, exhibit a similar sense of belonging.

"I love to come here," says Asmaa Hamed, a mother-of-three who came from war-torn Sudan six years ago. "I learn new skills and feel like I have am achieving something. I have made many friends here. I feel part of this community."

She's sewing alongside Sandra Lashghary, a 60-year-old grandmother who has lived in Sighthill for most of her life. "The church brings people together," she says. "It's important that we welcome people with open arms. How would folk here feel if they had to leave their homes and flee thousands of miles?"

Holding all this together and providing spiritual guidance at services, prayer groups and Sunday school is the indomitable Reverend Jane Howitt. The multilinguist arrived here six months ago with almost 20 years experience as a minister and is determined to grow the reach of the church to ensure it serves its community in the most useful and practical ways. Yet she is aware that the sort of work that goes on here day in, day out, in one of Scotland’s poorest and most multicultural communities, is probably not what many of us would associate with the bread-and-butter work of the Church of Scotland.

This is the modern face of the Kirk. There’s no Sunday best being worn, no genteel garden fetes. But the work being done here is clearly vital.

Therein lies the dichotomy for the Kirk in the 21st century: while the services it provides have never been more in need, membership is dropping significantly and it is fighting to stay relevant in an increasingly secular Scotland.

That membership has been falling is nothing new, of course. But the recent Scottish Household Survey revealed an interesting tipping point: for the first time, half of those surveyed said they did not have a religion, up from 40 per cent in 2009.

The Church of Scotland was the biggest loser, with just a quarter of respondents saying they aligned themselves with the Kirk, down from 34 per cent seven years ago. Over the last 10 years, Kirk membership has fallen from 520,000 to 353,000. Membership of the Catholic Church has remained largely stable over the same period, perhaps bolstered by new members from eastern Europe. From 2010 to 2015, meanwhile, the number of ministers fell from 939 to 786.

In common with other religions and denominations, the Church of Scotland is often portrayed as old-fashioned, conservative with a small C and largely out of touch with modern society, a particular worry when you are the national church.

These are clearly challenging times for the Church, then, both socially and spiritually. But how does an ancient and fiercely democratic institution that doesn't believe in hierarchies stem the haemorrhage of members? And how can it stay relevant to a society that is changing so quickly?

Back at St Rollox, Howitt is aware of the national picture but it is the role of her parish that is uppermost in her mind. “This church is a beacon of hope,” she says. “The nature of the population of this area for a long time has been that it struggles with multiple deprivation. We are working with some of most marginalised people in society.

“The church is a place of hope and safety, a place that gives people purpose – that’s what so many lives lack, especially when you are marginalised, have been unemployed for years, are struggling with mental health or addiction problems, or are trying to hold your family together.

“To find a place that can help you find the strength to manage the rest of your week, that is very valuable. And because we have so many international people in this community, who have often suffered the terrible trauma of war, we have to think hard about how to serve them.”

Does she think people would be surprised to see the frontline nature of the work being carried out by the Kirk in her parish? Can communities like hers perhaps help change wider perceptions?

“Obviously the Church has changed because it is part of the society in which it exists,” she explains. “For those who no longer have a real connection with it, their impression is based on historic experiences – that’s where the breakdown in understanding what the Church does now occurs, I think.

“For those who have a living connection with the Church, there is no breakdown in understanding. They are part of it, have lived the changes.

“The heart of church has not changed – the faith in Jesus Christ, that has remained the same. What has changed is the way churches express what the Church is about. It needs to reflect the needs of a changing society. What we’re doing here at St Rollox is responding to the needs of our community.”

Dr Ian Bradley, a minister and divinity lecturer at the University of St Andrews, says people are wrong to assume the Kirk isn’t moving with the times. He agrees that the Scottish Household Survey figure marks an interesting tipping point, and admits he’s not surprised it is the Church of Scotland that is suffering most.

“As the national Church, the Kirk has long been identified as being as much to do with social custom and upbringing rather than a particularly strong sense of religious allegiance,” he explains. “For a long time people would have put 'Church of Scotland' down as a badge of national identity.

"Catholicism and the smaller churches are hanging on a bit better. But Protestantism by its nature is interesting, in that it is easier to slip from it into agnosticism than from Catholicism because it encourages people to think for themselves and it is more open.

"Also, there’s nothing specifically Scottish about this, as almost exactly the same thing is happening with the Church of England.”

Bradley insists the Church still has a key role to play, especially when it comes to helping the elderly, the poor, lonely and vulnerable. And he believes thinking creatively about the nature of spirituality in the modern world could provide a new way for this old institution to thrive.

“Many urban churches are on the very frontline of society in terms of helping people in times of need,” he adds. “We see that in how they are helping refugees and those facing terrible poverty, vulnerable women and others. Some of the interfaith work is also very important.

“This type of work is important, too, as it engages young people and their activism and idealism. Involvement in social justice will become increasingly important as the Church moves forward.

“The Church also should be encouraged to get more involved in pilgrimage, spiritual adventures that focus on mindfulness and meditation – I think mindfulness is a profoundly Christian thing.

“There’s a lot the Church can do. We should not abandon the traditional service, but I think one has to realise that this appeals largely to older people and it’s not necessarily going to pull in younger people. Perhaps something that offers a different type of individual experience, perhaps even something more mystical, is going to appeal too.

"For many younger people, spirituality is expressed more individualistically, perhaps on social media and through other means. The Church has to link with that without losing its fundamental sense of community.”

At the same time, however, he is keen to retain and build upon the Kirk's special role as the national church. “The Church has a place in events and milestones we all go through in life such as weddings, funerals and Christenings. And also Remembrance Sunday – those occasions are hugely important for the Church of Scotland because we are representing the nation and the un-churched majority.

"Some of those who say they have no religion will be in church on Remembrance Sunday, just as they will be on Christmas Eve. They still have a yearning for something spiritual to express deeper values.

“The Church has a huge opportunity and a privilege, really, as the national church, to try to articulate and represent those values.”

We recently saw this national role play out only a mile south of St Rollox at a church that couldn’t be more different. Glasgow Cathedral has stood in the east end for more than 800 years, the only cathedral in Scotland to have survived the Reformation. Its Gothic grandeur represents perhaps the most recognisable symbol of the Kirk in the city, and it still plays a particular part in the historic and spiritual life of Glasgow, as well as attracting thousands of tourists.

It's not only Christmas that brings non-churchgoers in, of course. Times of grief and tragedy also draw people – both religious and non-religious – to the Church, and if anyone knows about the challenge and responsibility involved in responding to this, it is Dr Laurence Whitley, the cathedral’s minister for the last decade.

It was the cathedral that helped bring a focus to the grief in November 2013 when a police helicopter fell from the sky on to the Clutha Vaults pub in Glasgow city centre, killing 10 people and injuring many others. Whitley held a special service two days after the crash, attended by relatives and friends of the dead and injured, the emergency services that had worked so hard to save lives, senior politicians from all Scotland’s parties and others simply seeking solace.

I reported on the service and although not religious I remember being struck by how the tone and sentiment of the sermon, delivered in the ancient surroundings of the cathedral, accompanied by singing by the choir, brought a genuine sense of comfort to those in attendance, the vast majority of whom were struggling to make sense of what had just happened.

“The Church has both a national and local role,” Whitley tells me over coffee in the St Mungo Museum of Religious Life and Art, next to the cathedral. “I’ve been in the ministry for 42 years and every few years something arises when people look to us to express what the community is feeling. At times like this people are floundering, they are looking for someone to bring them together. That’s what the Church must try to do.”

He reminds me that the Church played a significant role in giving a voice to people who opposed the wars in Iraq and Afghanistan. It was also, of course, closely involved in the Scottish Constitutional Convention of the 1990s that is credited with developing the framework for the Scottish Parliament.

As for the Clutha sermon, I ask how you go about writing something that will reflect the feelings of the nation as well as bringing comfort to people. It can’t be easy.

Whitley thinks long and hard before answering. “You’re trying to reflect what people are thinking. What are they feeling? You’re trying to capture that. I wrote that sermon at 3am. The whole weekend was a blur. Everything was developing very quickly and the idea of a special service didn’t evolve until late on Saturday night. I just felt I needed to respond.

“People ask what you have to say from a religious dimension and that’s fairly straightforward: tragedies happen, illness and terrible accidents that Christians believe thwart the will of God.

"But more widely I tried to say that we are a city that has borne things for generations – I think too of the Clydebank blitz – and we will hold together. No other community can be better at standing shoulder to shoulder than this one.”

So, despite falling membership and the changing role of religion, the Church of Scotland, it seems, still has a variety of different roles to play. It just needs to work out how to connect with people.

It's ironic that perhaps the most traditional vision of the Church of Scotland I hear comes from the youngest person I speak to.

Kirsty Young, from Dunfermline, has been actively involved with Dunfermline Abbey all her life. Now the 28-year-old – one of the Church of Scotland's youngest elders – says she is keen to pass on the values she has learned to the next generation, daughters Zoe, two, and Isobel, nine weeks, and her nine-year-old step-daughter Ellie.

"The Church has been a major support for me over the years," she says. "I have so many friends I met through Church who are like family, so many wonderful people who have helped me with so many different aspects of life.

"And all this is even more vital to me now I am a mum. I want my children to grow up with the values I was taught – family-based values about helping where you can and treating everyone the same.

"I love the traditions associated with the abbey, the thought that it has been here for hundreds of years. There’s a way of thinking these days that organised religion is old fashioned, but I think that's a real shame. People are missing out on so much."