Though I wasn't raised in a churchgoing family, my husband and I joined our small-town Anglican church when we moved here. I've come to treasure it: the slow turn of the liturgical year, the opportunity to sing with others (a rare pleasure in the age of headphones and Spotify) and space to be serious with no particular goal in mind.

I was surprised at my own grief and anger when we were locked out of all this. In Mexico, worship mattered to large enough groups of people that clandestine lockdown services were organised, their times and locations passed on by word of mouth like illegal raves. But in Britain, faith is not considered worth the risk of illness -- even by the church itself. Nevertheless, lockdown seems to have given faith a boost, at least in its ersatz digital form: a quarter of Britons attended some form of online religious service during lockdown.

No one knows, though, if that revive the fortunes of in-person Sunday services in Britain -- or kill them dead. If the latter, it will be the culmination of a long-term trend. From a peak of over 10 million in the 1930s (then some 35% of the population), the proportion of Britons who are church members has been declining steadily. And the slump is not just in active church members, but believers in general. A 2019 British Social Attitudes poll suggested only 38% of Britons today even describe themselves as Christian, down from 66% in 1983. This fall is especially steep among the young: 2018 research shows that only 22% of UK young people today describe themselves as Christian.

This rings true. When we returned to church last Sunday, for the first time since lockdown, our daughter was the only child there -- in fact, she was the only person under 40. This is par for the course. Parents keen to get their young children into the attached Church of England school show up once a month to the religion-lite family service (which is mostly biscuits and Pritt Stick) and otherwise on Christmas Day at a pinch. There are never any teenagers. Twenty-somethings turn up sometimes, but generally only for a few weeks as the banns for their wedding are read.

Counting the grey heads around me in the pews (25 in total), it struck me that this church will probably cease to be a living community in my lifetime. Because ultimately a church isn't its surroundings, it's the people who turn up -- and if that doesn't renew, then it's not a church at all, just a building.

Today there are many such buildings. Some have been repurposed as gyms, restaurants, houses or even offices. Others have been left to crumble, or maintained, empty, by volunteers. Ed Sirett, an elder in Britain's last Mennonite church summed it up sadly in 2016 when the last, ageing remnants of his Wood Green church ended Sunday worship for good: "As with many Christian churches, we failed to convince the next generation that following Jesus was the best way. We lost the next generation."

I fear the same fate is approaching the Church of England. I feel acutely sad about it. But another part of me wonders if I'd have loved it in its heyday as much as I do now. For our established Church wasn't always the mild-mannered institution it is today, desperate for bums on seats, with congregations that smile indulgently when your toddler demands Pom Bears during the Eucharist.

In 1533, Henry VIII split from the Catholic Church to marry Ann Boleyn, and installed himself as head of a new Church of England. It was a time of religious ferment: Henry dissolved the monasteries, doling their property out to allies and triggering a pro-Catholic peasant rebellion. Meanwhile, radical Protestant sects multiplied, each with its own idiosyncratic take on the right way to believe and worship; names such as the mystical "Ranters" and the group of Protestant sects referred to as "Enthusiastic", convey a sense of a Christianity full of zeal and fiery vigour.

Barely more than a century after Henry VIII secured his royal succession at the price of excommunication, this heated atmosphere caught fire in the English Civil War. The conflict, which lasted from 1642 until 1651, was more a series of civil wars: bloody internecine struggles over the proper roles of faith, the monarch and the established church that divided families and killed 200,000 people -- around 2.5% of the then eight million inhabitants of the British Isles. The equivalent death toll today, as a proportion of the population, would be close to two million.

The scars left behind by the Civil War were unimaginably deep. In the ensuing decades, people blamed the febrile religious climate for its horrors. Fearful of relapsing into intra-Protestant infighting, the battle-weary of the 17th century establishment opted instead to unite against an easy outgroup: Catholics.

In 1688, facing the prospect of a Catholic dynasty under James II's newborn son, seven politicians and an Anglican bishop mounted a coup against him -- an event referred to since as the "Glorious Revolution". In effect, they booted James II out of London, then replaced him with his son-in-law, the Protestant William II, claiming that James's deposition was an abdication. Having gifted William the throne, they took the opportunity to clip his royal wings: under the Bill of Rights English monarchs would be constrained by Parliament, while the 1701 Act of Settlement barred Catholics from the throne. And thus was born the modern constitutional monarchy, with Anglicanism (and anti-Catholicism) baked in.

We get a hint of the deep fear of religious sectarianism this era left behind from the way the word "Enthusiasm" became a pejorative term, denoting religious excess or displays of elevated feeling, religious or otherwise. Other countries stereotype the British as emotionally uptight. What's less well understood is the way our national aversion to heightened emotion dates from the horrors of the English Civil War. Buried in our collective national memory is wall-eyed terror at the possibility that we might one day get overexcited and start fighting each other again.

Against this background, the Church of England's militant centrism is easier to understand. In its pomp, it was like a tyrannical patriarch, banging cousins' heads together and expelling dissenters -- Catholic or otherwise -- to enforce something like cohesion across a quarrelsome extended family. In middle age, it was sure of its righteousness and sternly conventional. In its latter years, it's been criticised for a new and incongruous wokeness.

But throughout that evolution, it's remained committed to the normie bourgeois morality and political establishment of its day. And by installing a degree of doctrinal flexibility and (importantly) middle-of-the-roadness in our moral and political centres of power, while expelling other beliefs to the margins, the Church of England has for centuries made it difficult for religious radicals to get a grip in the British Isles. In effect it functioned as a kind of vaccine against more extreme religious passions.

But even the most determined family peacemaker gets old eventually. It's hard to make a case for political legitimacy when only a handful of retirees turn up every Sunday. This isn't to say that faith is disappearing from Britain -- as I argued recently, religiosity is growing weirder and more vigorous -- but it's no longer finding expression in our established Church.

I'm not optimistic about that changing. Towards the end of lockdown, a group of people finally agreed that something moral mattered enough to risk spreading infection by gathering in public. But that group wasn't a church; it was Black Lives Matter. Whatever you think of that development, movements which change the world are those whose members are willing to risk death for their cause. In Britain right now, Christianity isn't on that list.

Humanists have long called for the Church of England to be stripped of its role in our political establishment. The smaller its congregations become, the harder it is to defend. And yet we underestimate at our peril the historic role it's played since Cromwell's day in keeping our religious passions in check.

I suspect the humanists will get their way, and also that we'll end up regretting their victory. I've seen no evidence to date that the decline in Christian belief and church membership is delivering a less credulous, less volatile, more rational and more measured public life. We may find that our departure from Anglicanism doesn't so much liberate us from faith as trigger a new proliferation of sects and pseudo-religions, all competing for dominance.

Without the relatively low-key hegemony of the Church of England, all limp handshakes and theological mildness, we can only hope we turn out to be less enthusiastic (in both old and new senses) than our 17th century forebears. Otherwise, the passing of Anglicanism as a political force may not be the end of English theocracy, but the moment it became a possibility.