Next month - the exact date keeps shifting - the Pope goes into hospital for an operation. The problem is said to be his appendix. But there is a feeling, backed only by rumour, that the lumberjack health and energy of John Paul II is breaking down at last. He is 76, after all, and he is visibly tired and infirm.

For a great many people, including many Catholics, a change at the Vatican would come as a relief. Karol Wojtyla has been Pope for almost 18 years now, and the complaints continue to pile up. He is perceived as authoritarian and reactionary. Early on, he suppressed dissent - the Jesuits have not forgiven him - and outlawed left-leaning theology. Although opinion in the developed world has changed profoundly during his pontificate, he has remained rigidly conservative on sexual matters. The bans on abortion, contraception, the ordination of women and marriage for the clergy remain as hard as they were in 1978.

Most of that criticism is fair. Whatever this Pope is, he isn't a liberal. But - speaking as a non-Catholic and unbeliever - I confess to a weakness for him. He was the first world figure to visit the United States and tell the American public that the fact that they wanted something - women priests, for example - did not necessarily mean they ought to have it. The Americans were incredulous. I think the Pope was wrong about women, but he was right to say that religion by opinion poll is worthless.

He also helped to destroy the Soviet empire. Carl Bernstein and Marco Politi have now written a book, His Holiness: John Paul II and the Hidden History of Our Time, claiming wildly that he worked in close alliance with President Reagan's CIA. But this Pope did not need codes and spies. From his first return to Poland in 1979 I watched him murdering the Soviet system, and he did it with words. He told the shabby, anonymous masses in front of him that they were individuals, each known to God, each precious, different and irreplaceable. They looked at one another, amazed, and then at their rulers. I remember one boy who said to me simply: "Nobody ever spoke to me before". Out of that surge of individual confidence came Solidarity, which knocked a hole in Communism below the waterline. And it duly sank, at first by inches and then with a sudden cataclysmic rush.

As everyone knows, the first act of this travelling Pope on arriving somewhere is to get down on his knees and kiss the ground. He does this because he believes that God created humanity in three concentric forms: as individuals, as families and as nations. To invade and crush a nation, in this view, is a sin against the divine will which is comparable to murder. It is this sort of Catholic nationalism which has landed the Pope in so much trouble in France, during the visit which ended at Reims last Sunday.

For him, France is a Catholic nation, "eldest daughter of the Church". A multitude of French Catholics, including the ultra-right nationalist Jean-Marie le Pen, agree with him. But a larger French multitude took the chance to disagree with quite unexpected fury. France, they said, has not been "a Catholic nation" for over 200 years. If this secular and republican France is anybody's eldest daughter, it is the child of the Great Revolution of 1789.

The Pope, through bad luck, had landed in the middle of a venomous French row about identity. As usual, this turned into a row about ancient history in which bits of myth were flung back and forth and genuine historians took cover. At the centre of the uproar was Clovis, King of the Franks, baptised into Christianity with his followers 1,500 years ago in AD496.

The root of the problem is that the French want to have their cake, eat it and also take it away from each other. They want to believe the legend of Clovis, "the first Christian king in Europe", as the token that France has always, everywhere been in the lead. At the same time, they like to boast that France through the Revolution gave to the world liberty, equality and the rights of man. But as the Revolution destroyed the monarchy and the Church, these boasts would be incompatible even if they were true. Trying to believe both at once gives the French a headache, leading to outbursts of irrational rage.

And not much about Clovis is true. The myth is that he conquered northern France with his Germanic tribe and exterminated or expelled the Romanised and Christian Gauls who lived there. He did nothing of the kind. Instead, he performed a typical Dark Ages feat known as "fictional genocide". In those days, a "nation" (gens, in Latin) required at least the appearance of ethnic unity to seem legitimate. So the local population, defeated by Clovis in battle, were persuaded without much difficulty to call themselves "Franks" and assent to the fiction that they had been wiped out. The Scots later reached just the same deal with the conquered Picts. In England, much of the Romano-British population probably became "adoptive" Saxons in the same way.

So "France" did not become a Christian nation in AD496. It already was one, apart from the foreign warlord Clovis and his gang. But the confusion runs even deeper. A thousand years later, after the Italian renaissance had rediscovered the classical contempt of "civilised" Romans for backward barbarians, the French began to wonder whether being "Frankish" was something to be proud of.

The pre-Revolution aristocracy thought that it was. They saw the Franks as a knightly race of mounted chivalry, and claimed to be descended from them - whereas the peasants were mere "Gauls" destined to be their subjects. (This was typical Eurocrap of the day. The Polish landowners boasted descent from Sarmatian nomad horsemen. And the English aristocracy grew arrogant about their cavalier "Norman blood", not to be mingled with footslogging Saxon stock.)

But at the Revolution, the French people opted to be Gaulish democrats. For the next century, the myth of national unity was built around "nos ancetres, les Gallois" - down to Asterix in our own times. Growing fear of Germany gave Frankish origins a bad press, while the Gauls seemed to have just that combination of free Celtic genius with Roman culture which the French self-image required. The Catholic, conservative part of the nation stayed doggedly loyal to Clovis. But radical, republican and anti- clerical France went mad for Gaul. The Emperor Napoleon III raised a colossal statue of the Gallic leader Vercingetorix over his fortress of Alesia.

Now, in post-modern times, French governments indiscriminately pile one "heritage" commemoration on another. The baptism of Clovis seemed to President Chirac an opportunity to display "roots", and he needed the glow of any ceremony which made France feel united. But the French - to their credit - suddenly remembered that "heritage" is not neutral, and that about some things they still feel very disunited indeed.

On a previous visit, the Pope boldly asked: "France, eldest daughter of the Church, are you still true to the promises you made at your baptism?". This time he received his answer from a nation of many faiths and none, which refuses to be personified in that simple way any more.

A few countries, like Ireland, Poland or Portugal, could still reply to such a question. But even those societies are growing reluctant to use a majority faith as a flag. The age of "Catholic nations" is over. What John Paul II said about the human being as individual will endure. But his map of the world, two-coloured between Christians and infidels, no longer helps even the faithful to find their way.