Christmas and Charles Dickens reached a lasting confluence in the national imagination long ago. The good cheer, the food and drink, the gifts, the crackers and the dancing which Dickens depicted in his Christmas scenes have become the stock images of our own Christmases, even today. Dickens lived them out in his own married family life too, at first. A wonderful description, repeated in the new biography by Claire Tomalin which will sit wrapped under thousands of Christmas trees, tells of how Dickens was a great conjuror, not just with words and scenes but with objects too. At Christmas 1843, the year A Christmas Carol was published, he delighted his guests by pouring raw flour, eggs and other ingredients into a gentleman's hat, performing a few magic words and gestures, and then turning out a cooked Christmas pudding on the table.

But Dickens's view of Christmas was far from the rosy-cheeked Victorian cliches that adorn Christmas cards. It was, in his eyes, a moral time. The seasonal message of A Christmas Carol, as Ms Tomalin points out, is a message of fellowship, not frivolity. The book is at once a protest against the condition of working-class life in 1840s London, and a moral tale in which even the worst of men can repent and become good. The presents, the feasts and the games are expressions of love and the mutual support of families and friends. There should be no embarrassment in recreating all this in hard modern times, providing that we remember its defiance of the everyday world too.

Yet Dickens is ours not only at Christmas. He informs not merely our customs but our minds and our language too. His characters – Miss Havisham, Scrooge, Fagin, the Artful Dodger, Mr Pickwick and Little Nell among the most obvious – are lodged in the collective mind. And as Robert Douglas-Fairhurst points out in his recent Becoming Dickens, the author is second only to Shakespeare in the bequests he left the language. More than 200 words and phrases owe their first appearances in print to him, among them boredom, butter-fingers, cross-fire, devil-may-care, dustbin, fairy story, footlights, funky, sharp practice, slow coach, snobbish, unyielding and whoosh. How many football pundits and managers, pontificating on a side's skills and weaknesses at set-pieces, know that set-pieces too is a Dickens invention?

The fraying of the old national culture and its reweaving into new forms is a timeless process. New generations of readers can find it hard to identify strongly with writers whose words were once shared points of reference. Milton, alas, is perhaps the greatest of the writers in English with whom the modern world is slowly losing touch in this way. Shakespeare is probably the greatest of those with whom the bond remains happily as strong as ever. But Dickens's reputation now stands higher than it has done for decades too. As the bicentenary of his birth in February 1812 rapidly approaches, his status as a still shared, still understood, still beloved and, above all, still read national writer appears to have hardened. In the end, the explanation for this lies in Dickens's writings themselves. His novels, stories and other writings retain in many ways an unrivalled power to excite, to amuse, and to move, sometimes by the sheer turnability of the pages – one wants to know what is going to happen to Esther Summerson, John Rokesmith or Pip – and often by the arresting power of an image – the river, the prison or the fog – or of an incident – like Oliver Twist asking for more. More than anything, though, Dickens's writings engage our sympathies because we identify with the rights and wrongs of what is happening.

That is why millions of people, by no means all of whom have read the novel, know and care about what Oliver does. And is why today, tomorrow and next year, he deserves the absolute Dickens of a celebration.