Faith and Reason: A tired man bends to kiss the Tarmac: A series on Catholicism starts this week, trying to discover whether one can claim to be Catholic without obedience to the Pope. The first contributor is Dr Eamon Duffy.

CLOSE your eyes and think of Catholicism. What is it you see? A wafer raised in priestly hands; a stern and weary man in white kissing the Tarmac of a hundred airports: a wino in the shopping precinct singing 'Danny Boy'; a crucifix in livid colour; abandoned crutches and plastic souvenirs at pilgrim grottoes; crafty, implaccable Italian Monsignori, all of these or none of these?

Asked to choose a single image of Catholicism, nine people out of ten might plump for the man on the tarmac, and the associations of obedience and discipline the Papacy carries with it. Lord Macaulay paid grudging tribute to the immemorial line of Roman Pontiffs, recalling an age when 'the smoke of sacrifice rose from the Parthenon', enduring still while all around the secular dynasties crumbled. George Orwell was struck by a resemblance to Stalin's Russia or Hitler's Germany. For both of them the universality, the Catholicism of the Church, was identified with its approximation to worldly Imperium - universal authority conceived as centralised power.

It is a perception Catholics have sometimes shared, though it is inimical to the real Catholicism which the Church claims. Catholicism is the proclamation to all times and cultures of the good news of God's indwelling of our world, and the overthrow in Christ of all the forces which make for human alienation. The substance and source of that proclamation, Jesus Christ and him crucified, is one and the same yesterday, today and forever. But living truth cannot simply be passed on inert and unchanged from generation to generation, culture to culture, like a baton in a relay race. The mystery of God was revealed not in a formula, but in a person, and it is passed not from hand to hand but from heart to heart. In its progress it takes on the living, breathing particularity of the peoples and the cultures who proclaim it. In Auden's phrase, 'The words of the dead are modified in the guts of the living.'

It is the genius of Catholicism to embrace and insist on both the complex diversity of times and cultures, and the possibility and necessity of a shared truth across them. Catholicism is a conversation, linking continents and cultures, and reaching backwards and forwards in time. The luxury of sectarianism, of renouncing whatever in the conversation cannot be squared with the perspective of one's own time and place, is not an option. The word heresy roughly means arbitrary preference. So far as it is a movement of rejection, the demonising of swathes of Christian experience by reference to some 'primitive' truth, heresy is the antithesis of Catholicism.

Nevertheless, the relation of the Church to truth is not miraculous, breaking through the limitations of earthly existence; it is sacramental, speaking to faith precisely in and through those limitations. And so the cultural and temporal universality of Catholicism is not a matter of cosmetic variation on something which is basically identical all the time - 97 ways of cooking powdered egg. It is a genuine and organic diversity, informed by a shared life.

So long as Catholicism was understood as a collective quality, pertaining primarily to the whole Church and only derivatively to its parts, the temptation to a totalitarian self-understanding was almost irresistible. Military discipline and the adoption of a single, divinely privileged culture, seemed the only way to ensure that so ill-assorted an army marched in roughly the same direction. So, the Church, it was claimed, could be seen to be universal because it possessed a uniform Latin liturgy, celebrated with the same gestures to the same music in the same clothes from Bali to Basildon.

Cynics dubbed this the argumentum de tourismo, summarised by saying that the great thing about being a Catholic was that no matter where you went in the world, you still couldn't understand what was going on at Mass. The itch for uniformity deep-seated in Latin Christianity was never completely successful. But it attained unprecedented and sometimes suffocating intensity in the age of the omnicompetent state and instant communications.

Since the Second Vatican Council it has been possible to explore again a far richer ecclesiology, and to recognise within the particularity of each local church the fullness of Catholicism. This model of Catholicism involves a polyphonic harmony, not the unison chanting of approved slogans. The result has been a rapidly developing pluralism of local liturgical usage, organisation and theologies. Not everyone has welcomed the shift. Under the present Pope the central administration has betrayed a persistent and depressing yen for a return to uniformity. Theologians have been disciplined, the powers of local churches curtailed, moves towards diversification checked.

In all this Pope John Paul II has been a key figure, and it would be easy to see his concern as the mere reassertion of proprietorial control over every aspect of the Church's life. 'I must go,' the Pope declared before his visit to England, 'it is my Church.' But this would be grotesquely to oversimplify a complex relationship. The unity of Catholicism must be more than a pious aspiration masking a centrifugal scramble into provincial concerns. Catholics are supported by each other, and also answerable to each other. In sometimes uncomfortable ways the papacy gives concrete expression to the interdependence of the churches.

This is inherent in the Pope's office, but even Karol Wotjyla's personal agenda - his unconcealed contempt for Western consumerism, his conviction that the experience of the Slav peoples under Communism offers a uniquely privileged insight into the Gospel - has served a prophetic function, enabling him to set question marks beside many of the most cherished preoccupations and assumptions of the West from the centrality of erotic fulfilment to the divine right of capitalism.

His outspoken presence has even on occasion made dictators or gang- bosses tremble and so has been a sign of hope to the oppressed which local churches from Chile to Sicily have not been able to offer, whether because they were persecuted or because they were compromised. Whatever its contradictions, the Papacy embodies both the demands and the resources of Catholic Christianity: left or right, we cannot quite do without the tired man on the Tarmac.

Eamon Duffy is a Fellow and tutor at Magdalene College, Cambridge, and author of The Stripping of the Altars, published earlier this year.