The eternally irritating Madonna doesn’t seem to realise that she’s pushing 50, and that the time has come to change her act to something more suitable, or to ride off the stage and into the sunset – hopefully without falling off her horse and cracking her funny bone again. Perhaps she does realise that the time has come to move on to quieter things and is panicking because of it. That happens to some middle-aged women: instead of trying to look good for their age and acting accordingly, they go into a hyper-panic, trying to look 25, which is impossible, and behaving like teenagers, which is foolish.

By carrying on exactly as she did when she was 25, Madonna doesn’t risk only ridicule but something much worse than that. She risks looking like a desperate woman who will take extreme measures to push up flagging record sales, and whose imagination is so limited that she can only come up with the same tricks she has been using for two decades.

The reason why Madonna comes across as pushing her luck, and the Rolling Stones, who have a combined age of 248, don’t, is not because society is more tolerant of men who behave like idiots than it is of women who do the same. It’s because Madonna is humourless, takes herself too seriously and tries too hard, but the Rolling Stones perform, on and off stage, in the spirit of self-parody and self-mockery. When it was reported that Keith Richards fell out of a coconut palm and was hospitalised for brain surgery, he sent himself up by telling journalists that it wasn’t a tree at all, but a shrub about five feet high. Compare that to Madonna’s big drama when she fell off her horse while pretending to be the Duchess of Cornwall. You can picture the Stones kidding each other about what they look like before they get on stage in their spray-on leather trousers and skinny shirts with plunging necklines. When they invited Marco Materazzi on stage at the end of their Rome show three weeks ago, Mick Jagger told the vast crowd: “Materazzi and Richards have something in common. They both had head-related problems recently.” You can’t imagine grim Madonna cracking a joke like that. Heaven forbid that anyone might think she’s funny and not Miss Whiplash.

The Rolling Stones wear their wrinkles and their sagging, saggy bodies with I-don’t-care flair. It’s not the same as being a slob, because they have style and iconic status, and it’s very, very different to being self-obsessed. The Rolling Stones would not be the same if they went under the surgeon’s knife on a regular basis, spent four hours with their personal trainer every day, talked to journalists about health foods and spirituality, and embraced one kind of weird religion after another, always while wearing an expression I last saw on my least favourite nun at school. Madonna does all those things, and that’s why her shelf-life is so much shorter than Mick Jagger’s. She tries so hard to be exciting that in the end, she’s just tedious.

Now she’s trying to sell herself when she’s past her expiry date by repeating exactly the same kind of stunt that shot her to the top of the charts and notoriety in 1985. But that was 21 years ago and she wasn’t even a spring chicken then. She was already 27 when she paraded around wearing very small clothes and very large crosses, singing Like a Virgin and playing up the fact that she is a lapsed Catholic who is called Madonna. And we all know that lapsed Catholics are very naughty because of all that repression about sex, don’t we? Take it from me – they aren’t, but then you don’t need me to tell you that. Unlike the people in Britain, the USA and Japan, you don’t have any notions about the sexual exoticism of Catholics, lapsed or otherwise, because you just can’t get away from them. I have absolutely no interest in the kinks and quirks of other people’s sexuality, but I think it’s a safe bet that crucifixes just don’t do it for Maltese men. On the contrary, they probably have roughly the same effect as an ice-cold shower in January.

This Sunday, Madonna will be behaving as though time has stood still for the last two decades, and will pull the crucifix stunt out of her gag-bag once more. She has called her current tour ‘Confessions’ (yawn) and her props are what they have been for 20 years: crosses and crucifixes (mega-yawn). When she performs in Rome, the headquarters of Catholicism, she will be lowered on to the stage wearing a sparkly crown of thorns and attached to a glittering cross – a kind of Barbie crucifixion, if you will. If her aim was to cause maximum offence and get plenty of attention, as she did when she was 27, then she’s got her wish. It’s more than a little bit different this time round, though. In 1985 she got away with it because youth and rebellion go together, but a 48-year-old woman dangling from a crucifix doesn’t look rebellious. She looks ridiculous. This is the fundamental mistake that Madonna makes. She thinks that because she’s still good-looking and trim, everyone will forget that she’s in her late 40s and carry on thinking that she’s 27 forever.

When you’re young and beautiful you can get away with almost anything. When you’re old enough to be a grandmother – and let’s face it, she is – no matter how beautiful you are, you will be dogged by the risk of looking desperate and foolish if you don’t move with the times. Madonna’s interpretation of moving with the times is keeping up with the current fashions for 25-year-olds, but what moving with the times really means here is behaving and dressing in a way that’s age appropriate. No matter how great-looking and in shape a woman is when she’s edging towards 50, she never looks like a 25-year-old. She looks great for 48, and that’s different.

Mick Jagger can get away with wearing a 25-year-old’s clothes not just because he’s thin and an iconic rock star, who has stayed relevant since the 1960s. He gets away with it because he doesn’t try to look 25. He’s a 63-year-old man dressing and behaving like a 25-year-old, but making fun of himself for doing it. He’s 15 years older than Madonna, and he has more staying power. He’s still whipping into a frenzy crowds of hundreds of thousands, but it’s a little hard to imagine what take-me-seriously Madonna will be doing at 63. Simulating lesbian sex with someone pretending to be Mary the Magdalene, perhaps, or being lowered on to the stage dressed as a gay John Paul II – or maybe by that time her kids will be old enough to stop her with the immortal line, “Stop it, ma – you’re embarrassing me.” One thing is certain, she won’t be posing naked in contorted positions for a book called Sex, as she did in 1992 – but then again, she might do. She’ll spend eight hours a day with her personal trainer instead of four, and reason to herself that if she’s thin and toned then no one will notice that if she weren’t Madonna she would be collecting a pension.

She has achieved something with her stupid crucifixion stunt though: uniting Rome’s Catholic, Muslim and Jewish leaders in disparagement of her behaviour. They have called it “disrespectful, in bad taste and provocative.” Yes, it’s all of that, but worst of all is that it makes her as ridiculous and pathetically desperate as any other middle-aged woman trying to behave like her daughter. Time is the only true democrat. Whether you are Mrs Nobody or Madonna, you can’t carry on behaving at 48 as you did at 28. Madonna’s behaviour is not condemnable because it is offensive to other people’s religious sentiments, but because it is foolish and stupid. Criticism on religious grounds will not stop her, but rather the opposite – it will serve as encouragement. She will only stop when she realises that we are laughing at her, and that she has become the pop world’s equivalent of the ageing lady who trawls the bars wearing too much make-up and too-tight clothes, and a little the worse for wear, thinking that she’s as much of a man-magnet now as she was in her hey-day. How sad that is.