The oath King Charles takes could affect not only the character of the relationship between Church and State, but also precipitate the pressures towards disestablishing the state church, which raises the question of who owns its resources.

The pressure to change the oath comes initially from secular sources who want to introduce two contemporary values. The first is in recognition of the secular sense that all truth is relative, and the second follows on from it, which is the imposition of the idea of equality. In this case, all religions are equal.

The problem is that the monarchy and its oaths are based on the values of previous generations which believed passionately that not only was Christianity exclusively true, but for reasons that were as politically cogent as they were spiritually important, that Protestantism was the truest form of Christianity.

Secular relativism wants to confront this - and it's the new philosophical creed for today's secular world. Several generations have been steeped/educated/brainwashed into it and the whole media is passionately committed to it. The trope goes: all religions are equal, aren't they? All values are relative. No one way to 'god' is better than any other, none is any truer.

The proposal is that the Coronation oath becomes one more mechanism to write this into the fabric of the beliefs that define our society and our social contract. The Coronation oath is, after all, one of the expressions of our social contract.

But it causes two problems. They may possibly be able to be contained, or they may have the effect of knocking down a whole line of interlocking dominoes.

The first problem is for the Church of England as the Established Church in terms of what it stood for. The problem for a state church is that it faces a perpetual dilemma in having a dual allegiance. Jesus taught that a person cannot serve two masters, when faced with God and mammon. But a state church is set up to serve two masters - the king of heaven and the king of the state. This can be managed if the state is in line with the faith. At that point both kings are aligned, and in theory to serve one may be to serve the other.

But what happens when the state changes its values and position? A wary and alert state church would realise that evangelising the society around it would be essential not only because Jesus had commanded it, but also because if society lost its alignment to the Christian faith the state church would be placed in the deeply uncomfortable position of having to choose between the two allegiances.

Inevitably some specific and contextualised 'conflicts of values' have emerged in history over certain particular issues. An obvious one in the last generation was when Bishop Bell of Chichester came out against the carpet bombing of German cities and the mass destruction of civilians. The moral fervour of Bell's wholly justifiable Christian position caused immense stress with the priorities of the government of the day as it pursued its aims to win the Second World War.

But in our generation what was confined to moments of stress and trauma between conflicting ethical positions, has morphed into a complete change in alignment of church and society as they have become pitched against each other.

Can a church retain its integrity for long if it adopts the wholesale relativism of secular egalitarianism? Doesn't it just become a transitory option on a scale of spiritualities? Is that enough to keep it alive in a hostile secular environment? The signs are that it may not be.

It certainly is not enough to justify keeping a role as an exclusive state church. And any move to inclusivity will have the effect of breaching its own identity with its past, and stripping it of its historical identity.

But whether or not the leaders of the church feel they can survive with any integrity or future with such a descent into relativistic irrelevance, the state may take a view on the privileges and status of a body that has become so amorphous and detached from its historical raison d'être.

A change in the Coronation oath would have major implications. It would inevitably raise the question of what such a church was for in society. This then provokes questions about disestablishment, and that in turn raises the impossibly complex issue of who owns what.

What is being proposed in practice about the Coronation oath?

The Constitution Unit of University College London has suggested that the government enact this change:

Will you in all your words and deeds uphold justice, mercy, fairness, equality, understanding and respect for all your Peoples, from all their different races, religions and cultures?

(Charles 3) I will.

Will you to your power maintain tolerance and freedom, including religious tolerance, and will you seek to uphold the rights of all your Peoples to observe their different religions and beliefs, without fear of persecution?

(Charles 3) I will.

The present Coronation oath, however, requires the Monarch to maintain and defend the established Anglican Protestant Church in England.

If the proposed amendment gets taken seriously - and the conversation is indeed a very serious one - it would firstly need primary legislation to repeal the Coronation Oath Act 1689, which requires the Monarch to maintain the established Anglican Protestant Church in England.

That would initiate a parliamentary debate. Would the outcome of that leave the C of E as the Established Church? It might not. And then the dominoes would start to tumble. How many and in what direction? Who knows.

But it also ought to be recognised that even if the oath were changed and the state church were left in place, official state Christianity would have committed itself to the defence and implied promotion of other systems of belief. Its hands would become more tied over evangelism than they are already - and its two major competitors, which are radical atheism and energetic Islam, have no such restraints.

The followers of Richard Dawkins and Sam Harris are not about to give up their absolutist commitment to relative values. The followers of Mohammad are not about to surrender their absolute belief in his status and role. It's only the liberal followers of Jesus who are buying this self-contradictory rhetoric that will make them irrelevant.

And it's not hard to imagine what the next turn of the cultural and political wheel would bring within a couple of decades, at the point when Charles III gives way to William V. If it doesn't happen now, it will then.

Gavin Ashenden is Associate Editor of the The Catholic Herald and a former chaplain to Queen Elizabeth II.