I believe that on Wednesday something odd happened. Probably 2.7 million people went to a Christmas service in their local Anglican church, a total that has risen steadily over the past decade. On Sunday, however, the number will plummet back to a weekly 700,000 and falling. Christian faith in the UK is in decline, with less than half of the population now believing “in God or a higher power”. Of these, just 15% claim to be “Church of England”, let alone go to church. Just 3%of 18- to 24-year-olds describe themselves as Anglican. The only booming churches are those catering to immigrant and minority ethnic communities. Adherents to Pentecostalism have risen by 40% since 2010.

The quality of therapy through meditating beauty should apply to most churches. But they need to offer more than that

Yet more people not only go to Christmas services, they also pack out England’s 42 Anglican cathedrals, whose worshipping congregations have grown some 30% since the turn of the century, even as church attendance has fallen by the same amount. This can be explained partly by a lingering family attachment to childhood ritual, and in the case of cathedrals by the appeal of music, especially the ever popular evensong. But clearly this gulf between the cathedral haves and the parish church have-nots is significant.

As a church-lover but not church-goer, I despair at the looming presence in the centre of almost every city, town and village of what the radical bishop of Worcester, John Inge, deplores as “locked mausoleums marginal to the lives of their communities”. A quarter of the 15,000 Anglican parish churches now have fewer than 16 worshippers, with a large and historic building at their disposal left empty six days a week. That building was paid for by the tithes of local people. The government rightly prevents it from being demolished, as embodying local identity, memory and craftsmanship. The prospect is of these churches going the way of medieval castles, to become barricaded vacant ruins, as Philip Larkin wrote, “A shape less recognisable each week / A purpose more obscure.”

I cannot believe they are beyond reuse. One avenue might be termed traditional. It lies in a recent survey of GPs who complained that they were becoming “the new clergy”. Ever more people have no symptoms beyond loneliness and despair. They say, “Doctor, I’m not sure there is any point to all this.” Doctors dare not prescribe churchgoing even for devout patients, though I am told some do have a priest on call. One practice in Cumbria is even a joint vicar’s/doctor’s surgery: “The vicar will see you now.”

I once visited a council estate in Leeds, where the vicar told me he was the last professional person living anywhere nearby. Teachers, doctors, social workers, police officers had all fled. His door was an all-purpose port of call for those in distress. He was alone on the frontline where the welfare state was in retreat, his priestly duty of dispensing comfort and support overlapping with that of the therapist and care-worker. For many people, there must be some complementarity between faith and healing. One thing to be said for the established church is that, unlike much of social care, it has not all but given up.

Another clue lies in the experience of cathedrals. Sanctity as such is clearly no barrier to popularity. While a few, such as Peterborough and Guildford, are in financial trouble, most English cathedrals are doing fine. Everywhere they offer catering, shopping and a performance stage. There has been golf at Rochester, skateboarding at Gloucester, a helter-skelter at Norwich. Liverpool is never still. St Albans is the cultural focus of its city.

Somehow, cathedrals have contrived to snap free of the sectarian exclusivity of the parish church. They answer to a longing for congregation and communal space. Their key is a quality unfashionable to social analysis, the offer of solitude with beauty. You need not to be of faith to sit quietly and contemplate the loveliness of a cathedral. As a dean once hinted to me in a whisper, “Here we don’t bang on about God.” The sociologist Grace Davie described a cathedral as “vicarious religion”, somewhere an individual can be private, undisturbed and uplifted by architecture and music. To Davie cathedrals catered to “a desire for anonymity, the option to come and go without explanation or commitment”. They are psychotherapy in glass and stone.

This quality of therapy through meditating beauty should apply to most churches. But like cathedrals they need to offer more than that. As shopping streets collapse and village and town centres decline, many churches will be the last place of congregation left standing. Some are already branching out as concert halls, meeting rooms, coffee shops, schoolrooms, even post offices, though desperately few. None to the best of my knowledge is a pub.

There is no reason beyond determination – and over-rigid planning – why churches should not revert to what they were in the middle ages: one-stop shops for every local service, for advice, therapy, support and company for those in need. This applies especially in rural areas, whose residents are increasingly elderly.

I am familiar with the objections. The Church of England must hold a world record for institutional negativity. That is why these buildings must be freed from their present “nationalisation”, and move into the control of parochial councils, trusts or social enterprises, as in Germany and Scandinavia, where they can levy an (optional) local church tax. They must have a primarily secular future.

There will always be churches. Those who want them for worship need not fear. Reviving in them a sense of both wonder and purpose might even lead some people from Christmas back to God.

• Simon Jenkins is a Guardian columnist