Is atheism the new opiate of the masses? The momentum for this question had begun long before the new Liberal Democrat leader, Nick Clegg, this week answered the BBC Radio 5 Live question, "Do you believe in God?", with a simple: "No." It was already under way before everyone forgot to feel affronted by the influx of seasonal e-cards wishing us all a Happy Holiday, and then comprehensively failed to notice that the mighty M&S had left out Jesus from its 2007 Christmas card collection. The traditional Christmas school holiday period had already morphed into "Winterval" in an increasing number of Scottish local authorities.

Earlier this month, a survey commissioned by the public theology think-tank Theos revealed that more than one-quarter of British adults could not identify Bethlehem as Jesus's birthplace, guessing Nazareth or Jerusalem instead. Only 12% could answer all four questions about the Christmas story correctly.

The Theos survey followed an earlier Sunday newspaper revelation that only one in five schools planned to perform a Nativity play this year. The apparent de-Christianising of modern multicultural Britain compelled at least one commentator yesterday to describe 2007 as the year "the swelling tide of unbelief crashed further through the structures of our cultural architecture".

Commenting on his survey, Paul Woolley, director of Theos - which was launched last year with the support of the Archbishop of Canterbury, Dr Rowan Williams, and the Cardinal Archbishop of Westminster, Cardinal Cormac Murphy-O'Connor - said: "Such survey results do not prove the existence of an atheist plot to take Christ out of Christmas. The argument that the growth of religious pluralism demands of us particular sensitivity and consideration of others is a serious one - even when made by secularists who are willing to use some faith groups (with whom they have little affiliation or sympathy) to silence others.

"The result, however, is that in our desire not to offend we water everything down to an inoffensive but characterless lowest common denominator and, in the process, erode the public's knowledge of the very festivals that an educated, plural society is supposed to understand and recognise."

In an online debate, Woolley went on to say that in the case of Christmas, ignorance threatened to erode the cultural ties that bind, and secondly to remove some of the few remaining obstacles to a fully consumerised society. And he conceded: "No-one seriously thinks that being a Christian or a member of the established Church is the same thing as being British today."

One of the things that made Mr Clegg's atheistic declaration remarkable was that it distanced him from PM Gordon "son of the manse" Brown, the church-going Anglican Conservative leader David Cameron and one of his own predecessors, David Steel, also a son of the manse. But even more remarkable, perhaps, is the lack of outrage at his statement.

Perhaps the way had already been paved by the UK release in November of The Golden Compass, the first in children's author Philip Pullman's Dark Materials trilogy to be made into a Hollywood film. Co-starring Daniel Craig and the self-professed Catholic Nicole Kidman, it is number one in the UK film charts - despite being criticised by the Vatican newspaper l'Osservatore Romano as being "the most anti-Christmas film possible" owing to its anti-God storyline: the sinister, controlling forces from which the orphan child Lyra Belacqua attempts to save the world bear a remarkable resemblence to organised religion. Pullman has stated that his purpose in writing his books was to undermine belief in God.

The Vatican's main objection to the film is its abandonment of hope. "In Pullman's world, hope simply does not exist because there is no salvation," said l'Osservatore's editorial.

Hope, of course, is the key to Christian faith. In his Christmas message, Mario Conti, Archbishop of Glasgow, reminds the faithful of His Holiness Pope Benedict's assertion that we are "saved by hope".

Those who choose to cling to their old-fashioned religious faith in the rising tide of atheism will no doubt say "Amen" to that.