At first sight, the best reason to be grateful for the monarchy may be because it keeps us free from a president. Presidents are political creatures, and politics is a dirty business. Politics does not easily succumb to redemption.

But we are not just political animals, we are, as CS Lewis once famously wrote, amphibious. We are half animal and half spirit. We are, to put it a bit more carefully, 'embodied souls.'

And while part of us understands the need for a political head of state, within Christendom there has developed this sense of a monarchy that is in some way associated with the holy, and connected with God's purposes for a people.

Royalty asks for and then claims the blessing of God to engage a king or a queen to act as head of state. In so doing, it infuses into the state a Christian perspective in which monarchy bridges the gap between the political and the religious.

Why does this matter? CS Lewis once again got to the heart of it when he observed in his collection of essays called Present Concerns: "Where men are forbidden to honour a king they honour millionaires, athletes, or film-stars instead: even famous prostitutes or gangsters. For spiritual nature, like bodily nature, will be served; deny it food and it will gobble poison."

Celebrity culture is something that we both deride and revere. We deride it as vacuous and self-serving, and yet our society consumes it voraciously, and as Lewis warned, poisons itself with the superficiality and irrelevance of it. But it appeals because for a moment the celebrities have attention and the power of influence that goes with it.

Celebrity culture has become a drug that we know we ought to be free from, but we turn back to for a hit. When we look back at the example Queen Elizabeth set in terms of the Christian values she lived by, we see something entirely different.

She exemplified selflessness, the discipline of duty, the importance of the other, the joy of service, the values of forgivenesses and patience.

As King Charles III succeeds to the throne, he steps into the gap that she left, and reinvigorates the monarchy in its position as a guardian of value in our society and culture. This acts as a challenge to celebrity culture and political power, and to some extent as an antidote to it.

But can the monarchy survive in giving us a hereditary Christian head of state? There is no guarantee that it will.

There was a shattering moment following the death of Diana, when a very odd form of mass hysteria grasped the nation, and for a moment the Queen, Charles and the royal family were in danger of becoming enemies of the state. They were certainly enemies of the state of mind of a large proportion of the population, who were demented with grief at the death of their heroine.

It was only the swift and decisive actions of the Queen which defused some of the rage and allowed the dangerous moment to pass.

When he was asked what he feared most in government, Prime Minister Harold Macmillan replied, "Events dear boy, events."

We do not know what problematic events lie in the mists of future history before our new King, Charles III.

We do know that in his first speech to the nation he was generally thought to have expressed exactly the right tone and sentiments. He captured the hopes of the nation and in so doing, morphed or transitioned from a prince to a King before our eyes.

But the monarchy embodies values that have become increasingly different or even opposite to those that the swift and powerful progressive tide of culture have imposed on us recently; and particularly the Diversity, Inclusion and Equality agenda.

In the last few years, this agenda has been launched like a public re-education programme though all the institutions of our state. From a Christian point of view, understanding why this simplistic and badly defined, unrealistic utopianism has gained such a profound grip on our society is not easy to understand in rational or intellectual terms, though less hard to explain spiritually.

At every point of friction with the culture it sets out to replace, it chooses Christians and the Church as its first target. Diversity does not include Christians, and neither does inclusivity or equality.

The monarchy may find itself in trouble because in the West it is essentially a Christian concept. It provides a symbolic, psychological and spiritual restraint on the raw ambitions of politicians, and does so by making itself accountable to God, his Church and Christian values.

But Christian values are under sustained assault. So if King Charles means what he says in his oath to act as Defender of the Faith, he may find that he places himself in both the spiritual and political firing line in the culture wars.

At the same time it is hard to think of an institution that is less acceptable to the progressive culture of Diversity, Inclusion and Equality. Monarchy is confined to a single hereditary line. It could not be less diverse if it tried. It excludes anyone not born into the royal family, and excludes everyone in that family who is not the monarch or their heir. It has no concept of equality, but instead embodies hierarchy, with the monarch at the top of the pyramid of privilege and everyone else below.

Both King Charles and Prince William have tried to gain social credits by demonstrating their Green credentials whenever they could, but that may not be enough to protect the monarchy from the malign eye of the Cultural Marxism that turns its wrath on everything and everyone that resists its demands.

One might even consider a future situation where one of the faithful Christians, like the teacher recently imprisoned in Northern Ireland, appeals directly to the King as Defender of the Faith to offer support to his plight?

What would the King do then? What would happen if every Christian as they were sacked, excluded, expelled or marginalised, appealed directly to the King who had taken an oath to be Defender of the Faith, to defend them as their Christian witness and integrity was attacked?

If the oath excluded any concept of defending those who were paying a price for defending the faith themselves, would it continue to have any real meaning? And if one very significant and public part of the oath of accession had no real meaning, how much else of what the monarchy stood for could be said to be authentic?

As Macmillan warned, it will be the unforeseen and unforeseeable events that bring crises to a head.

Perhaps a Conservative government might foresee the coming crisis and take the view that it has to decide between the ill-drafted Equalities Act, a driver of so much progressive agenda, and preserving the monarchy.

Whether or not increasingly beleaguered Christians, slowly but surely being marginalised by the state, do or do not invoke help from the Defender of the Faith, some restraint on the progressive assault on what remains of the values of Christendom may be required to avoid a greater clash of symbolic values.

If not, the monarchy may find itself collateral damage in the ruthless march of a secular and political ideology that proclaims itself inimical to anything overtly or even covertly Christian and non-secular.

As a casualty of Meghan Markle's campaign of revenge, the royal family found itself wholly unable to defend itself against even the unspecified accusation of 'racism'. If ever it should find itself more dangerously fixed in the crosshairs of progressive utopianism, it may be hard put to defend itself against a cultural and political critique. Its survival is not guaranteed.

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