It is no secret that religious freedom is under a lot of pressure in Western countries at the moment. A highly controversial ruling in Canada's Supreme Court in June found that depriving graduates from a distinctively Christian university of professional accreditation was justified because such an institution was inherently discriminatory. This was despite religious freedom being an expressly enumerated constitutional right, and the ruling standing in clear conflict with existing legal precedent. Closer to home in July, a Catholic priest in Scotland was sacked from a university chaplaincy post for giving expression in a service to his Church's teaching on sexuality.

It is dismaying to see religious freedom struggling for life in the countries which pioneered it. The most important reason must surely be the growth in non-belief and irreligion. For what is the surest foundation on which religious freedom may rest? Is it not the solemn recognition of that great first duty of the moral law, to honour one's Creator in accordance with one's best understanding of what it requires?

As James Madison famously argued at the birth of the American republic: 'It is the duty of every man to render to the Creator such homage and such only as he believes to be acceptable to him. This duty is precedent, both in order of time and in degree of obligation, to the claims of Civil Society. Before any man can be considered as a member of Civil Society, he must be considered as a subject of the Governour of the Universe.'

It isn't difficult to see how an excess of irreligion will undermine this critical foundation of religious freedom. If too many people no longer accept the reality of God's existence then society as a whole will begin to lose sight of the importance of allowing people conscientiously to render him his due. Increasing numbers of people will instead regard religion as nonsense (at best) and have little time for it. Some, we can hope, will continue to support religious freedom because they understand the significance of religion for humanity and what is at stake in its disappearance. But more and more will be motivated to support not so much freedom of religion as what is sometimes mistaken for it, freedom from religion – the extirpation of the influence of religion as much as possible from society, and particularly from any spaces that could be construed as public.

This hostility to religion is given increased impetus by the abuse scandals that have rocked various religions in recent years. Such terrible abuses of trust and power, while by no means limited to religious organisations, are much more likely than in other contexts (such as education, social care, media or entertainment) to lead to calls to jettison religion as a whole – as witness Guardian columnist Polly Toynbee this morning.

There is something of a paradox here for supporters of religious freedom. Religious freedom permits people to embrace irreligion, yet irreligion isn't so good at returning the favour, since it is typically hostile to religion and apt to dismiss it whenever it clashes with fashionable views. To address this problem, at least in part, it is necessary for believers to ensure that the first duty to honour the Creator remains a staple of public life, and does so, as far as possible, notwithstanding the growth in irreligion. To do otherwise, even as a concession to increased secularisation and loss of belief, would be to surrender the logical and moral ground on which religious freedom stands. And not just religious freedom, but the moral law more generally, with all the personal freedoms it underpins – freedoms of conscience and speech and assembly, alongside key ethical commitments such as truthfulness and human dignity. It is after all very difficult to regard anything as sacred when the Source of sanctity itself is disavowed.

But why should those who disbelieve in God support public expressions of the first duty of honouring God? Aren't they rather more likely to regard them as unwelcome impositions of falsehood and superstition on the public realm? Indeed, many do just that. But perhaps some can be persuaded that the reasons that believers have for their belief – the rational need to account for the order of the universe, for instance, and the origins of the universe, and the origins of life and consciousness and morality – give them, as non-believers, a reason for recognising the importance of the first duty for humankind, even if not for them personally.

If God does exist, they might say – and it's not totally out of the question to think that he does – then honouring him would clearly be of the utmost importance, so religion ought to be respected. Or, if this is too much of a stretch, perhaps some will see the benefits that they and society derive from respecting religion in terms of personal freedoms, cultural traditions and moral values, and support the first duty to honour God as a useful myth on instrumental grounds. Whatever stance non-believers may take, though, believers can be clear where they stand, and why they regard the first duty as a logical and moral imperative in public life.

What does the first duty mean in practice? In essence it means the state and other public bodies striving to maintain a basic sense of respect for the Creator of humanity, or at least for some notion of transcendence, in the conduct of their affairs. Often this can be done in general terms, such as by making generic references to God in public life and official pronouncements, and by guaranteeing equal rights for religious adherents, and proportionate treatment of the various religious groups in society (or at least those friendly to religious freedom – any wedded to the use of force for religious ends are naturally another matter).

Sometimes, however, it needs to be acknowledged that the state and other public bodies will have need to lean on one religion in particular. This is where things can get a bit contentious. Many people don't like the idea of one religion being favoured or privileged in this way, and question whether, given religious freedom, it is really legitimate or beneficial to do so. However, the fact is there are times when it only makes sense for the state or other public body to lean particularly on one religion – normally the society's main or historic religion, the tradition most deeply entwined with its culture. Such as, for example, when participating in official ceremonies or recognising public holidays. Or when needing to identify a lead in the provision of religious services, or when seeking advice on religious or moral matters. Or when wanting to hold up to the population at large a default religion to help them avoid falling into folk superstition and irreligion.

In these sorts of areas attempting to draw on more than one religion will quickly run into problems of being practically unwieldy, socially untenable or culturally illiterate, or some mix of all three. Yet leaving religion entirely out of the picture here, secularist-style, could only encourage irreligion in the population and neglect the first duty in public life. The importance of religion and the crucial part it plays in human life – engagement with the transcendent dimension of human existence – would become regrettably absent from the public forum.

It is important to recognise that we are not talking here about imposing religious law. That would be contrary to religious freedom, not to mention an affront to human freedom and reason more generally. We are talking only about respecting the role of religion in human culture and ethics and not treating it as something that must be made artificially invisible in the public space.

Unwarranted curtailments of religious freedom by courts and others such as in Canada and Scotland will continue as long as the public culture remains stripped of its religious foundation. Christians need to be at the forefront of restoring to public life expressions of the first duty of the moral law – to honour the Creator of the universe – not least through religious freedom, the better to secure freedom for all.

Dr Will Jones is a Birmingham-based writer, a mathematics graduate with a PhD in political philosophy and a diploma in biblical and theological studies. He blogs at www.faith-and-politics.com and is author of Evangelical Social Theology: Past and Present (Grove, 2017). He can be found on Twitter @faithnpolitic