Britain's country churches must change if they are to survive through the 21st century, according to the leading art historian Sir Roy Strong.

Sir Roy, launching a £10,000 award for the best-adapted village church in tomorrow's Country Life magazine, says village churches are still among the "immemorial icons" of England but he warns that they are facing "impending cataclysm".

England's 10,000 village churches, most of them listed, are under threat as never before and their future can no longer be taken for granted, warns Sir Roy, an inveterate "church crawler", committed Anglican and former director of the Victoria and Albert Museum.

"Nestling at the heart of the village, people are instinctively drawn to its weathered stone and lichen, the overgrown churchyard and topsy-turvy muddle of ancient headstones," he says. "Here, in the midst of a rural community, is a building which is not only a testament to the Christian faith over the centuries, but the repository of everyone’s past, a place of memory and reflection. In the bustling and rapidly changing world of the 21st century, this building more than any other is the ultimate symbol of the continuity of the English village."

Today's churches are failing to justify their existence, he says. "Shut for most of the week or even month, and only attracting congregations of any size at Harvest Festival, Remembrance Sunday and for carols at Christmas. Those are not enough to justify the expense of saving such a building," he says.

If the 20th century was about saving the country house, a cause to which Country Life magazine had devoted dozens of issues, this century will be about ensuring that the rural church has a future, he writes.

Shortly after he became director of the V&A in 1974, churches formed the subject of "Change and Decay: The Future of Our Churches", one of the three great heritage exhibitions which spanned the decade. The two other exhibitions in this series were on country houses and gardens.

In the case of the country houses and gardens, the exhibitions were instrumental in reversing the decline and they are no at the heart of flourishing heritage industries. But the same cannot be said of churches.

"As a consequence, 30 years on, we are faced with an impending cataclysm," warns Sir Roy. "You only have to look at the average age of the worshippers, not to mention the small numbers attending in so many churches, to realise that we are heading towards a terminal situation in so many instances. Add to that the lumping together of as many as five to 15 churches and foisting them on to a numerically diminishing clergy, and the future could hardly look more threatening."

Sir Roy, who says it is his intention to stir up the villages of England over the future of their ecclesiastical heritage, says: "The world must realise that, if the much-loved parish church is to survive, it will have to change."

Parish churches would have disappeared years ago, along with the village post office, shop and bakery, if they were subject to normal commercial pressures, he says. In many villages, the church is the only communal building left.

"As a result, for villages with a vibrant community, there is an opportunity of a kind unseen for more than 500 years to put their church right back at the centre of village life. This is the one remaining building which you can all share, in which your history and your identity is etched deep. But it calls for daring and imagination of a kind which, surely, the English have never lacked. Given their value to the village, however, parish churches often remain desperately underused."

Lack of funds held both by the Church of England and Government to prop up the medieval and sometimes older churches, and with declining congregations also feeling the pinch, Sir Roy argues that a wider purpose has to be found for a building built to service a now vanished rural society.

Sir Roy, who in his recent book on country churches describes how he left his own country church to attend the more vibrant Hereford Cathedral, says: "These days, churchgoers like me get in the car and go to the church of their choice. That is the reality of this consumerist age. The signs are that there is a shift in the pattern of churchgoing in favour of the larger churches, cathedrals, minsters, abbeys and the greater parish churches where the congregations are bigger, the music fine, the liturgy well conducted, and where there is a warm ministry of welcome."

He says this marks a pattern of churchgoing similar to that a millenium ago, when many villages were without churches.

"To my mind, the key word opening up a future is ‘adaptability’. We need to find ways in which the country church can be adapted to serve as the hub of its village, as well as remaining in liturgical use."

Such radical shifts of use have happened before. In the 16th and 17th centuries, churches were torn apart in response to the dictats of the Reformation. In the 19th century, churches were transformed to meet the demands of the revived spirituality of the Oxford Movement. Something similar needs to happen in this century.

"I don’t underestimate the fact that for many, this will be painful," warns Sir Roy. "But much of this arises from misplaced notions as to the sanctity of the interior." Unviable churches should be turned into houses, museums or even picturesque ruins. Where churches can be viable, villagers should form a trust to look after them and put together a plan of action, he advises.