EVERY year, newspapers carry a story about nativity plays which reflects the preoccupations of the time. Last year, I recall, it was something about how tea-towels on the heads of shepherds were being replaced by ready-made outfits from the supermarket shelves. The nation's schoolchildren had become embarrassed by their mothers' homemade offerings. Designer wear was as de rigueur on the school stage as it was in the playground. Cue laments about the commercialisation of Christmas.

This year something more unsettling is in the air. The Church Times last week reported that, according to a survey of 2000 parents who use the website Netmums, only a third of primary schools now hold traditional nativity plays. Instead, schools are doing Winter Celebration plays in which the children are appearing as fairies, recycling bins, sprouts, drunken spacemen, Lord Sugar, or Elvis - sometimes alongside a Mary and Joseph.

What is wrong with that in a multicultural society? The day after the survey was published, I picked up a clue in a restaurant where several festive office parties were clearly already taking place. On the table was a laudable little card, inviting revellers to add £1 per table to their bills in aid of a charity for the homeless named Streetsmart. But inside the card was an exhortation from Stephen Fry, which began "Most of us don't say Grace these days because we don't know who to thank. . ."

The jazzed-up, augmented Nativity/winter-festival amalgams have something in common with Mr Fry's approach. Both are determined to sideline Christianity, and yet both seem unable to achieve their ends without borrowing from religion, albeit with a subtext of implied criticism.

You would have thought it possible for Mr Fry, who glories in the title of Distinguished Supporter of the British Humanist Association, to make an appeal for the homeless by presenting it as a self-evidently worthwhile act. Instead, he chose to frame this act of human solidarity as a counterpoint to a religious view of the world.

This is very odd. Like so many other modern atheists, instead of standing on his own moral feet, for some mysterious reason he appears to feel the need to see secular altruism as some kind of implicit rebuke to religion. Why the two cannot exist side by side, independently, in their own right, is unclear - especially since the New Atheists are constantly insisting that you don't need to be religious to be moral.

We live in a pluralist society; so it is understandable that some head teachers might want to create an end-of-term performance that includes all their pupils. But why do they need to mess about with the nativity story? Why don't they just do a panto?

Perhaps because, as Pope Francis warned, a nation "which is no longer open to the transcendent dimension of life" is a nation "which risks slowly losing its own soul and that 'humanistic spirit' which it still loves and defends". Perhaps the Netmums parents intuitively understand that - which is why two-thirds are unhappy that their children's schools have stopped holding a traditional nativity play.

Paul Vallely is the author of Pope Francis: Untying the knots.