Count the number of times you see or hear the phrase “peace on Earth” in the next week or so. It’s one of the great Christmas themes – or great Christmas cliches, if you want to be cynical. But in the year when we remember the centenary of the end of the first world war, when the image of mass graves for millions is fresh in our minds, it needs to be more than a seasonal bromide.

Yemen: up to 85,000 young children dead from starvation Read more

It’s not even as though British involvement in war were a thing of the past. Thank God, most of us have not directly experienced in our lifetimes the impact of full-scale war; but our official policies are still helping to support large-scale slaughter and long-term misery elsewhere in the world. Think of Yemen, where up to 14 million people are on the edge of famine as a result of a war that continues to claim countless lives; a war in which the UK government is complicit through its sales of arms to Saudi Arabia. These arms sales have increased by two thirds since 2016, and now account for nearly half of Britain’s major arms exports.

A report published today by the charity Christian Aid on the UK government’s double standards highlights the painful tension between our words and actions about building peace and the volume of arms-related British exports we continue to take for granted. About half of our development spending goes to states and regions affected by chronic violent conflict, and about half of our arms exports go to states where military force is used against its citizens or vulnerable neighbours. It’s as if we are creating, or at least helping to maintain, the very conflicts whose terrible effects we then spend money on mitigating.

This is both economic and moral nonsense. Sustainable development needs political security and the rule of law. It means people having a safe place to call home, a secure food supply and guaranteed access to medical and educational services. The best use of our aid budget will always be in projects that create this kind of stable environment – which means that peace-building is an intrinsic aspect of development. If we want to avoid wasting our foreign aid funds, we must invest in secure institutions, just process, and above all the avoidance of armed conflict. We cannot do this if we are at the same time unapologetically resourcing war.

So we are calling for an immediate review of UK sales of arms to states that are actively infringing international law and human rights by pursuing murderous campaigns against their own citizens or their close neighbours. We are challenging the UK government to take a new lead in promoting peace and the rule of law in such contexts – to follow through the logic of its aid spending by recognising armed conflict as the source of so many development challenges. This means not only stopping arms sales to certain nations but positively investing in programmes that build intercommunal and international cooperation, effective post-trauma support, training in mediation and conflict management and robust civil society institutions.

This is what we are saying in Christmas cards that our supporters are this week sending to the foreign secretary, Jeremy Hunt. And we say this with all the more force because the findings of a new poll conducted for Christian Aid by ComRes show that nearly three quarters of British citizens would support an end to arms sales to countries engaged in indiscriminate slaughter (three out of five are against selling arms to Saudi Arabia so long as it continues its activities in Yemen). There is a similar majority in support of development programmes being guided by the immediate needs of people on the ground, not just by security priorities as Britain chooses to define them.

Food, clothes, medicine: the people of Yemen just want the same life as us Read more

Britain is currently struggling with political near-paralysis as it tries to find a way of handling a problematic majority vote. But there is, in relation to our global context, what seems to be a clear national consensus about how we can become transformative leaders in this conflict-ridden world – a clear majority supporting better and more coherent approaches to sustaining peace. Will the government and the political class listen? Nearly 70 million people worldwide are displaced because of violent conflict, and the number is steadily rising. We need to go to the root of the problem and act promptly and effectively.

Otherwise “peace on Earth” will indeed be little more than a cosy cliche. For Christians, the coming of Jesus into the world spells the beginning of a new awareness of human possibility, human dignity. It is an exhilarating promise – but not just a matter of “comfort and joy”, because it demands honesty about the depth of suffering caused by war, and courage and patience in confronting it.

• Rowan Williams is the chair of Christian Aid and a former archbishop of Canterbury