I'M CERTAINLY not in favour of banning or burning books, but there are a few books in this world which would make even the most fervent liberal twitch for a box of matches. For me, it is not the 120 Days of Sodom or Mein Kampf that marks the outer boundaries of acceptability, but something infinitely more poisonous and corrupting.

If I were going to lock away a single thing in the private cabinets of the British Library, have a work of literature removed from the shelves of bookshops and schools everywhere, it would have to be something widely thought of as innocuous, and perhaps even beneficial. It looks like a fairy story about some nicely behaved children, a wicked witch or two and some talking animals, but it is the sheerest poison. Let us drop CS Lewis and his ghastly, priggish, half-witted, money-making drivel about Narnia down the nearest deep hole, as soon as is conveniently possible.

In fact, I'd more or less assumed that these frightful books had stopped being read years ago. It turns out that this year marks Lewis's centenary and, to mark it, the Royal Shakespeare Company, no less, is putting on what promises to be a spectacular stage production of the first book in the Narnia series, The Lion, the Witch and the Wardrobe. Spectacular in setting, I presume, since nothing on earth could make the products of Lewis's mind intellectually spectacular, or even interesting. They are revoltingly mean-minded books, written to corrupt the minds of the young with allegory, smugly denouncing anything that differs in the slightest respect from Lewis's creed of clean-living, muscular Christianity, pipe- smoking, misogyny, racism, and the most vulgar snobbery.

I think I knew there was something wrong with the books when I read them as a child. I couldn't have identified their blunt allegory (the Creation in The Magician's Nephew, the Crucifixion and Resurrection in The Lion, the Witch and the Wardrobe, Armageddon in The Last Battle) but I knew that here were some books with some fairly unhealthy designs on me as a reader. All that guff about Deep Magic and Deeper Magic when that lion comes back from the dead struck me as cheating with the plot, and still makes no sense unless you import great loads of Christian doctrine into it. To be honest, I'm still pretty vague about a lot of Christian doctrine, which is probably why great swaths of the series make absolutely no sense to me at all. What on earth is The Last Battle going on about, with that donkey and Plato and the poor girl who gets sent to hell for wearing nylons and lipstick? What is its doctrinaire bullying doing in a book for children, and why did people ever think of it as appropriate reading for the under- 10s?

The books embody some pretty unpleasant social attitudes. The loathing of vegetarians, socialism, anti-smoking and "cleverness" is a recurrent theme; the racism is extreme, even by the standards of the time (you would probably gather from A Horse and His Boy and The Last Battle that Islam was some kind of Satanic cult). You just know that if Lewis were alive today, he would be writing idiotic, sniggering articles about "political correctness" for The Daily Telegraph. But I think the most corrupting feature of it all is the poverty of the imagination. It is often thought that these books are richly imaginative pieces of work. They are not; they are thin, doctrinaire tracts of social and religious instruction, which allow no dissent, and which embody only the bullying voice of their author.

Other books of the time look fairly dubious, if judged by contemporary standards. It's easy to have problems with the racial attitudes of The Lord of the Rings, with those heroic, tall, blond Elves talking Welsh, and the ghastly dark, squat, hairy little Orcs with their Turkish consonants. But, to some extent, Tolkien is rescued by the variety of his imagination, and by a vision which, if it is not rich or profound, is at least intricately patterned and satisfying. Those Narnia books, instead, are second-hand, commonplace, and allegorical in the most boring way. They serve as vehicles for a narrow-minded man's pet obsessions, and, with their second-hand props of fauns and centaurs, can only make a child think that literature is something that can never be surprising.

Don't give your children CS Lewis to read; not the Narnia books, not the Screwtape Letters, not that appalling Is God an Astronaut? science fiction. It looks like rich fantasy, but it is the product of a mean, narrow little mind, burrowing into their ideas and pooh-poohing them. Give them anything else - Last Exit to Brooklyn, a bottle of vodka, a phial of prussic acid, even Winnie the Pooh - but keep them away from The Voyage of the Dawn Treader.