Catherine Pepinster: Pope John Paul could learn a thing or two from Donatella Versace

Earlier this year, thanks to the Pope, I wasted my money. During a visit to St Peter's in Rome, I stopped in a Vatican gift shop and bought my friend Lucia a string of pink, pearly beads – a rosary. Lucia, a devout Catholic, has a fondness for rosaries rather akin to other people's fondness for stamps, or railway timetables, or Art Deco china: she's collected close to 100 of them. They are all the same, in that they all have the same number of beads, each representing prayers and events – called "mysteries" in the life of Christ. Now the Pope has just rendered them all redundant. He has decreed that there should be more prayers said, and more events to be remembered. Poor Lucia is going to have to spend even more time on her knees, and acquire some much longer strings of beads.

To the non-believer, the rosary is as much a symbol of Catholicism as nuns and confessionals. But, just as few women become nuns today and the queues at the confessionals barely exist, so the rosary has gone out of fashion. The Pope, though, is a devotee, and he has decreed that the rosary should be extended – for the first time in a thousand years – with five new "luminous" mysteries relating to five significant moments in the life of Christ. This, he and his cardinals believe, will revive the rosary's fortunes. Well, it might bring extra money flowing into the Vatican's coffers as the devout dump their old beads. Perhaps its gift shop will put up signs: "Get your new improved, version here. As seen on TV and recommended by John Paul II."

But revive its fortunes? The rosary has been going out of fashion for, well, as many decades as there are prayers on the string of beads. It's unpopular and unhip and no amount of papal edicts will make it otherwise. Even most of the Catholics who own rosaries keep them in the boxes they arrived in as christening presents, and they will stay there until it's time to wrap them around their fingers in their coffins.

Yet they could become desirable and interesting. Religious artefacts are still embraced as motifs and symbols in art and fashion. If the Pope really wants the rosary to be popular, he needs it to become a must-have. And that means it has to rival the most wanted item around – the cross. Take a look, for example, at the Versace show at the Victoria and Albert Museum which opened last week with the Patsy-Sophie-Chelsea-Madonna brigade out in force. The major retrospective celebrates Gianni Versace's brash, flash talent, together with his sister Donatella's later additions. It also reveals the exquisite workmanship of the Versace designers: intricate beading, painstaking stitching, stylish cutting. And there amid the finest silks and satins are crosses and crucifixes. The Versaces are not the only designers who embrace the cross in fashion: Tom Ford at Gucci has created a beaded choker, complete with crucifix, retailing at £335. His Gothic style has made the cross one of this season's most desirable accessories.

Not that the Pope will be particularly pleased about that either. Earlier this year the Vatican criticised celebrities such as Catherine Zeta Jones and Naomi Campbell for abusing the significance of the cross. But the very fact that so many people choose to wear it, endorses the cross as a still potent symbol in these post-Christian times.

Take David and Victoria Beckham. They spent £40,000 on a matching pair of white gold crucifixes encrusted with dozens of diamonds. Yet the England captain is not one for traditional theology. He once said of his son Brooklyn: "I want him to be christened, but I don't know what religion yet."

What the Vatican forgets is that religion does play a role, albeit an unconventional one, in people's view of the world. It does have significance – if not the sort of significance the Vatican would prefer. If the Pope really wants the rosary to be popular, a call from Rome to Milan's fashion houses might be in order. After all, a Catholic such as Donatella has probably got one at the back of her drawer, still in its christening gift box.