A new campaign to open the leisure centre in Stornoway on Sundays is the latest skirmish in the ongoing battle between religion and secularism

• Those who oppose Sunday opening for the centre insist many islanders – religious and non-religious alike – support the Lewis Sunday, enjoying the tranquility it brings. Picture: Jane Barlow

In any other part of the UK, the pool would be replete with children splashing each other and clambering over inflatables; the soft play area would be a frenzy of ball-throwing fun. But this is Lewis – a fiercely Presbyterian place where religion holds sway over everyday life and enjoying yourself on the Sabbath is frowned upon.

So – though the Western Isles recently topped an obesity poll, and many pubs on the island are open – the leisure centre doors have been locked every Sunday since it was built in 2004.

While those living in Barra, Benbecula and South Uist (which historically are predominantly Catholic) have access to their pools seven days a week, the 20,000 people on the Hebridean island of Lewis and Harris (who belong to the same local authority) have to make do with six. Councillors cite the importance of the fourth commandment – Remember the Sabbath day and keep it holy – in support of their decision.

Now, however, the growing number of secular people and more liberal Christians are on the warpath. Angry their lifestyles are being dictated by a minority of staunch believers, they have banded together to fight for change. Having sent in petitions and letters to no avail, keen swimmer ten-year-old Ellen MacLeod plans to take legal action against Western Isles Council, arguing she is a victim of discrimination. Ellen's family have sought the opinion of top legal firm Ross Harper and are in the process of raising the 40,000 needed to allow her to fight the precedent-setting civil case.

"We are very conscious of health issues and want our children to be living an active life, and Sundays are the perfect day for swimming," says Ellen's mother, Elma, a paramedic, who has two other children, Glen, seven, and Charlie, five.

"Both parents are home, the shopping and other chores have been done and the football has been played, and yet we are not allowed to go. In the winter, too, the weather may be cold and wet and there are only a few hours of daylight – and there's nothing for the children to do," she adds.

Like most of the campaigners, Elma, who was born on Lewis, respects the right of those who go to church to observe the Sabbath. "I have no problem with those who want to practise their religion doing so. But if the pool was open, what difference would it make to them? They wouldn't be forced to use it. What I don't understand is, if I can respect their views, why can't they respect mine?"

Like the controversy over Sunday ferry sailings – which was resolved last year when, to the outrage of the Sabbatarians, Caledonian MacBrayne sent its first Sunday ferry over the Minch to Ullapool – debate over pool opening hours has caused ill feeling in the community. Those who oppose Sunday opening insist that many islanders – religious and non-religious alike – support the Lewis Sunday, enjoying the sense of tranquility it brings. "Obviously, the main principle here for us would be a religious one – that the Bible insists that one day of our week is given over to the things of God rather than to secular things, to our own pleasure," says Dr Iain Campbell, the chairman of the Lewis branch of the Lord's Day Observance Society. "That is our starting point. But there is also tradition and our culture. "

But the campaigners insist that, in offering residents in different areas different access to amenities, the local authority is abusing its powers. "I think there are two separate issues here. Religion is one thing and the law of the land is another," says Christine Macmillan, a retired dentist, who has had first-hand experience of the poor state of many children's health. "The pool being open or not being open is a civic thing, but we are all paying council tax. I've never heard it said that Lewis and Harris are paying less council tax because they only get to use the amenities six days a week and so I question the morality and ethics of that."

The row over the swimming pool is the latest skirmish in the ongoing battle between religion and secularism which has been raging in Lewis and Harris for a generation. With its four separate Presbyterian churches – the Free Church, The Free Presbyterian Church of Scotland, the Associated Presbyterian Churches and the Church of Scotland – the island has been described as the last bastion of Calvinism in the UK. Lewis and Harris contain about 20,000 people and 43 Presbyterian congregations (as well as three Scottish Episcopalian churches, a Catholic church and a Baptist one).

Not so very long ago, the swings in playgrounds would be chained up on Sundays, and even today, there are parts of the island where hanging out your washing on the Sabbath will bring snide remarks. In recent years, of course, things have started to change. Playgrounds are accessible, many of the larger pubs and restaurants are open – and the ferries ply their trade between Ullapool and Stornoway, allowing islanders to spend the weekend on the mainland.

The churches and the Lord's Day Observance Society, however, remain implacably opposed to any further erosion of the traditional Sunday and use their influence to try to shape council policy. Only last week, the Stornoway Golf Club was refused a licence to open its bar on Sundays after the Free Church of Scotland reminded the Western Isles Licensing Board "of their responsibilities before the higher court of Almighty God and of the reality of their being called to account for actions which will further permit the desecration of the Lord's Day".

The last time the council discussed the swimming pool, the vote was 18-11 against seven-day opening and – despite mounting pressure – it has refused to review its contentious policy.

"There has never been a custom of opening sports facilities on a Sunday in Lewis and many people value this way of life," a council spokesman says. "The councillors here have much smaller constituencies than in many other places and are very close to their communities. The majority of them take the view the leisure centre shouldn't open on a Sunday."

In the meantime, the obesity problem continues to grow. In 2008, a "fat map" created using data from Scotland's 14 health boards showed the Western Isles had the highest proportion of patients with body mass index (BMI) of 30 or over. The swimming pool is open until 9:45pm most nights and the council has introduced an attractively-priced membership scheme, but that has done nothing to appease the campaigners. "We work, we have young kids, we come home, get tea, put them to bed, so extended opening hours in the evening doesn't really help us," says Michael Smith, who has two children, James, six, and Erin, four.

Michael, who works in education, believes the Sunday closing means a lot of children are missing out. "These days lives are more hectic during the week than they were 20 or 30 years ago and that's why weekends are all the more important. The pubs are open. If you are a parent, you can go down the pub and watch the football and leave your family at home, so why is your family prevented from doing something healthy?"

For 17-year-old Rebecca Gunn, who is sitting her Highers, the problem is that the limited opening hours means the pool is full to bursting point on a Saturday. "It's full of younger children – that can be a bit offputting. There is a small section set aside for people who want to do lengths, but it does get congested," she says.

Having exhausted all other channels of communication, most campaigners now see a court case as the only means of securing change. "If you observe a particular religion and this is what you want to do, then that is fine, but that doesn't give you the right to tell the public to live like that," says Elma. "These men and women (the councillors] want to be our spiritual guides, they think they are in charge of our religion, our beliefs, but they're a local authority."

Her daughter, Ellen, was refused legal aid on the grounds that – since many people would benefit from a successful outcome – all those in favour should put together to fund the case. So her family have had no option, but to try to raise the money themselves. They have already had donations – including one of 1,000 – but have a long way to go. If they succeed, their lawyer, Cameron Fyfe, thinks the prospects for success are high. "We would base the case on the Equality Act 2006 which says that if you are a public authority and you are providing services to people, you can't discriminate among the users and that is what this council is doing because they are treating the inhabitants of Lewis (and Harris] differently than those on the other islands," he says.

"Our second argument, which is a common law argument, is that you can seek a judicial review of a council's decision if you can show that no reasonable council would have come to this decision. I think we can easily show that there is no other council in the country which has come to this decision."

In the meantime, Ellen, who has won medals, has just one wish: to be allowed to swim more often. "I love swimming," she says. "When the pool's closed, I draw or watch television or play the computer, which can be fun, but it's not as healthy.

"I don't understand why I can't go swimming on a Sunday. I just don't think it's fair."