Tony Blair and George Bush came under sustained attack from the leaders of the Anglican and Roman Catholic churches yesterday over their growing threats to take military action against Iraq.

In his first Christmas message, Dr Rowan Williams, the new Archbishop of Canterbury, made a withering criticism of "strategists who know all the possible ramifications of politics, miss the huge and obvious things and create yet more havoc and suffering". It was those that society regards as "wise men" who "can't help making the most immense mistakes of all", he said.

Two thousand years after Christ was born, he said, "communications are more effective than ever in human history; analysis of national and international situations becomes ever more subtle; intelligence and surveillance provide more and more material. We have endless theoretical perspectives on human behaviour, individual and collective. And still the innocent are killed."

His speech, Kneeling in the Light, which was to be broadcast on BBC Radio 4 just after midnight last night, coincided with an appeal by Pope John Paul II for an end to "blind violence" in the Holy Land and concern from the leader of Britain's Catholics, Cardinal Cormac Murphy-O'Connor, that war was being seen as inevitable.

Dr Williams' message was characteristic of the style of the new Archbishop, who is to be enthroned in February. It rooted its view of the modern world in the insights of the Bible but also used contemporary culture.

Dr Williams spoke of a "whole world grown old in intrigue and violence, cynicism, despair and false hope" – which raised questions about how those qualities are manifest in those leading the military build-up against Iraq. "It's as if the wise, the devious and resourceful, can't help making the most immense mistakes of all," he said.

Contrary to BBC reports yesterday, Dr Williams did not "mock" Western leaders but offered them an alternative. "Yet – here is the miracle," he concluded, "the three wise men are welcome. You might expect that a faith which begins in such blinding simplicities, the child, the cattle, the barefoot shepherds, would have no place for the wise men in their massive foolishness. But they were not turned away."

Mr Blair has defended the Archbishop's right to speak out, but his broadcast is likely to increase tension with the Government. David Blunkett, the Home Secretary, criticised Dr Williams on Tuesday for suggesting consumerism is driving morality out of politics. Mr Blunkett said there were "contradictions" in the Archbishop's Dimbleby Lecture last week, adding: "The assertion that modern governments ... order [people] is nonsense."

David Hope, the Archbishop of York, said yesterday that war as a matter of resolving international disputes was incompatible with the teaching of Jesus. But he added that, because of Iraq's disregard for UN resolutions, "it may yet become necessary to contemplate some form of military intervention".

Cardinal O'Connor, the Archbishop of Westminster, said people should not assume war against Iraq was inevitable and urged world leaders to work toward a peaceful solution to the crisis.

"We must never give up and assume that war is inevitable," he told worshippers at Westminster Cathedral. "Let us pray today, therefore, that each one of us, particularly those involved in international diplomacy and politics, will maintain our permanent commitment to building and maintaining peace in our world."

Pope John Paul II kept up the Vatican's campaign against war in Iraq during his Christmas Day message by calling for efforts to snuff out the "ominous smouldering" of conflict in the Middle East.