When Pope Benedict addressed the clergy of Rome on Thursday, he chose to talk to them about the Second Vatican Council, perhaps the central event of his life.

He is among the last people alive to have taken part in that momentous gathering and it is a privilege of the long-lived to rewrite history. The then Joseph Ratzinger played a leading role in the revolutionary changes brought about by what Catholics call Vatican Two, but then did a theological U-turn after witnessing with horror the more secular upheaval of 1968.

He and his predecessor, John Paul II, have step-by-step reoriented the Catholic church to the point that it is nowadays an institution which might dismay the pope who convoked the Council, John XXIII, and reassure his austere predecessor Pius XII.

So the election to the papacy of a conservative African or Asian prelate would, in principle, be welcome to large sections of the church in Europe and the United States. Even for the dwindling minority of liberals, it would be a reminder to the world that, overall, Catholicism is growing, and at a faster rate than the global population.

But traditionally-minded Catholics might see one major change resulting from an African pope; the tradition of priestly celibacy.

Because of that tradition, combined with the contemporary intolerance of the laity towards unmarried relationships between priests and their «housekeepers», it would appear that the number of gay men in the Catholic priesthood has increased. Sharon Ferguson, chief executive of the Lesbian and Gay Christian Movement, said: «A lot of gay young men brought up in Catholic households see the priesthood as a potential answer to the question: ‘Why aren’t you married yet?'» In one of his earliest moves, pope Benedict barred sexually active homosexual men from studying for the priesthood. Yet, three years ago, using hidden cameras, the Italian news weekly Panorama captured priests in Rome visiting gay clubs and bars and having sex.

That sort of thing would run into very vigorous opposition from the kind of no-nonsense African and Asian cardinals being touted as candidates for the throne of St Peter. Their attitude – of revulsion towards homosexuality – could, however, prompt a distinctly non-traditional reform. However, time and again, bishops on visits to Rome have stressed that, in many African cultures, a man without a woman beyond a certain age incites suspicion and lacks authority.

That puts a Catholic priest at a notable disadvantage to the local imam in many of the areas where Christianity is competing with Islam for ascendancy. And since that is one of the most important challenges facing the church, a black pope could put an end to priestly celibacy.