Last Night's TV: Am I bovvered? Yes - and bored as well

The Catherine Tate Christmas Show, BBC1; The Hidden Story of Jesus, Channel 4

Sometimes comedy needs to be predictable to work at all. As the camera closed in on the gravestone of Lauren Cooper, the brat's brat and the victim of a kayaking accident, you knew it would carry more than the stark details of name and dates that you initially saw. Indeed, any viewer who is not educationally subnormal should have been able to guess at the wording that was revealed as the camera panned down to take in the epitaph. Even so, it was quite funny when you saw it: "I still ain't bovvered." That's part of the point of catchphrase comedy, after all. You know precisely where you're going, it's how you're going to get there that is novel. But such predictability can be dangerous territory, because the border between the deliciously familiar and the tediously repetitious isn't marked clearly. One moment the audience are hugging themselves at their knowledge of a comic character, the next they're griping that they've seen it all before. Sadly, The Catherine Tate Christmas Show spent far too much time on the wrong side of the frontier.

One explanation of what had gone wrong arrived with the final credits. Just three writers got a namecheck, which by my reckoning is too low by a factor of around 10. Because while yuletide specials are made in pretty much the same way as a normal episode - with added decorations and some celebrity guest-stars - they're not watched in the same way. We expect them to bulge with treats and novelty, to indulge us as excessively as everything else has on Christmas Day. And if they actually seem to stretch the usual material a little thin, the audience may well get restive and tetchy. You started by smiling at Tate's Nan, cackling like a malfunctioning Gatling gun, but found that smile congealing as it became clear that the schtick was exactly the same as always: chortling sweetness to people's faces and a torrentof foul-mouthed abuse behind their backs. Even the appearance of Kathy Burke as her daughter, showing exactly the same lethal two-facedness, didn't really refresh the sketch, since it hung around for at least 30 seconds after you'd surfeited on its gamey flavour. Other attempts to add something new to old favourites were even more counter-productive. In a sketch featuring the couple who can barely talk because they find each other so hilarious, three of the woman's girlfriends turned up, all displaying the same gleeful incredulity at the most banal events. It was as though Tate had determined to prove to us that she wasn't unique, and pretty much any jobbing actress could do as well.

I found myself unwillingly channelling Mary Whitehouse while I watched the programme, as sketch after sketch resolved itself with a curiously violent obscenity. It isn't that I have anything against obscenity per se - in fact, I rather missed Peter Capaldi this year, blistering the paintwork as Malcolm Tucker. It was just that there was something joyless and desperate about these punchlines that actually seemed to want to punch someone. Anyway, the revenant spirit of Mary was a little confused that this entertainment, scatological and foul-mouthed, should be going out on BBC 1 while Channel 4, spiritual home of the scabrous affront to middle England, had given more than two hours of its schedule for a long documentary about the life and teachings of Jesus.

Not that Mrs Whitehouse would have approved entirely of Robert Beckford's The Hidden Story of Jesus, which concluded with its presenter announcing that "it doesn't matter whether you believe in the Virgin birth, the Resurrection or even the Nativity". Instead of doctrinal dogma, Beckford was hoping to offer us a kind of syncretist religion, happy to blur the distinctions between the world's great faiths and concentrate hard on their shared values.

In pursuit of this, he travelled the world to look for similarities between theChristian narrative and other scriptural traditions - something that isn't particularly hard to do. In Vrindaban in India, centre of devotion to the Lord Krishna, he watched Hindu nativity plays, complete with a Herod-like king and a guiding star. Further north, he talked to Buddhist monks about Guatama Buddha's miracles of walking on the water and feeding of a multitude. He also explored the belief that Jesus had survived the Crucifixion and gone off to live in India, though he never clearly said whether he actually believed this himself, or just found it a useful way to enlarge Christ's potential market penetration. His film interestingly blended an argument for the surrendering of sectarian division with continued evidence that religion sanctions precisely such hatreds in the minds of many believers.