THE centenary commemorations of the First World War, which begin this year, offer every parish church a unique opportunity to engage with members of the community, young and old, in ways that perhaps only parish churches can. We should seize the moment. If clergy and congregations have not already thought about possibilities, there is time.

Each of the next four years can provide a distinctive focus, from the outbreak of war to the peace of Versailles, by way of evocative campaigns and battles; we need only to set our imaginations working. As an example, let me recount a project from a church where I was once parish priest, and then offer a suggestion for the future.

Our inner-city church had within it a war memorial. It was first dedicated in the 1920s, and commemorated by name the (mainly) young men of the parish who had lost their lives. A second and shorter list of names was added after the Second World War. Many churches have such memorials inside or outside the building.

The idea for the project began when the head of history at a local secondary school asked whether she could bring pupils into the church to look at the memorials. The pupils were studying the First World War, and she wanted to make this more real through a local connection.

THAT was the starting point for a project that subsequently involved a local history group, two subject areas at the school, the church's uniformed organisations, the British Legion, members of the congregation, and people in the parish.

We recruited the history group to research some of the names on the 1914-18 memorial and to liaise with the school. They came back with a wealth of information: who the men were, their occupations before the war, their military history, their families, and how and where they died. Many fell in a single campaign - the Somme, in 1916.

They found some family members still living locally, and soon had sepia-coloured photos to put beside the names, many of which were also found in the church's baptism records. There were poignant stories of young lives lost.

Some descendants were interviewed, and a rich archive of stories, photos, and memorabilia was built up. The history group and the young people prepared an exhibition of what they had found, which was displayed in church.

In addition, the school's art department was invited to produce pictures and collages for display in church, reflecting on war using themes suggested by the Stations of the Cross - betrayal, cowardice, abuse of power, fear, love, the vocation of mothers, cruelty, evil, hope - and more. This was probably the first time that some students had engaged closely with the Passion story or any New Testament text.

Activities culminated in the weeks before and after Remembrance Sunday. Many young people made repeated visits to the church with friends and family. The Remembrance Sunday service included a brief account of the life and death of one of those named on the memorial, and young people read lessons they thought appropriate.

COMMEMORATING the First World War should not be left to cathedrals, or involve only civic dignitaries and the armed forces. Churches can respond in many ways: let me suggest one.

The Great War was hugely significant: it led to the collapse of empires, and the re-drawing of boundaries. It changed the balance of power between Europe and the United States. It contributed towards the emancipation of women. It also led to soul-searching about war, not least among Christians. Rediscovering something of this history can help people to be more thoughtful about conflict now.

Memorials to the Great War illustrate one way in which our predecessors made sense of it. On the whole, war was not glorified, although the death of those who fought was understood as a laying-down of life for the sake of others, in the way Jesus laid down his. What was remembered after the war was sacrifice, not victory; the national annual commemoration is held at a cenotaph, not an Arc de Triomphe.

That interpretation helped people to deal with the pain of loss: death was not a waste, but a sacrifice. This has remained the language through which those who lose loved ones in today's conflicts also find solace. There are few better ways of understanding that emotion than singing and reflecting on the hymn "O valiant hearts".

THIS was not, however, the only Christian reaction. Faith was challenged by the Great War. Some lost their faith; others found it again by understanding God's relationship to humanity differently. The rough and, at times, raw rhymes of Geoffrey Studdert Kennedy (a decorated military chaplain who became a pacifist) capture this change (Faith, 23 May). He thrust aside older traditions of the impassibility of God - a God who remained above the suffering - and found instead a "Comrade God" (the title of one of his poems): a suffering God, a crucified God. Although it caused controversy at the time, it was a theology that reshaped all subsequent Christian thinking.

In our day, young lives have again been shattered in conflict. People are again thoughtful about war. A valuable service can be performed by the parish church if it can help that reflection. It can be done in the context of an exhibition or a service, if the contrasting responses in the Christian community after the Great War are held together: "O Valiant Hearts" and "The Comrade God".

In this way, the church finds and fulfils its vocation of ministering even to those who are not present every week, and who are not all of one opinion.

Canon Billings's book The Dove, the Fig Leaf and the Sword: Why Christianity changes its mind about war, is published by SPCK.