African bishops and cardinals attend Mass at the conclusion of their synod in Rome, October 25, 2009. Photograph: Vincenzo Pinto/AFP/Getty Images

The Jesuit theologian Karl Rahner once said that, in the long run, the importance of the Second Vatican Council in the mid-1960s is that it marked the emergence of Catholicism as a self-consciously global family of faith. Rahner was making a kind of theological argument. What I want to argue is that Catholic demography in the early 21st century confirms empirically what Rahner contended theologically.

At the dawn of the 20th century, there were 266 million Catholics in the world, of whom 200 million lived in Europe and North America and just 66 million (25 percent) lived on the rest of the planet, principally in Latin America. In other words, roughly a hundred years ago, the demographic profile of the Catholic Church was essentially what it was at the time of the Council of Trent in 1545—overwhelmingly white and First World.

By the year 2000, the balance had shifted. With 1.1 billion Catholics in the world, almost 66 percent of them lived in what is loosely referred to as “the South” (including Latin America, sub-Saharan Africa, the Indian subcontinent, Southeast Asia, and the Pacific islands). Roll the clock forward to 2050, and the projection is that the South’s share of Catholics will rise to 75 percent—a figure that sums up the most rapid and profound transformation of Catholic demography in 2,000 years of Church history. The period we are living through now is comparable to that moment in the first century when St. Paul left Palestine for Damascus, Greece, and Rome, thereby transforming primitive Christianity from a sect within Palestinian Judaism to a religious movement.

The question is: As southern Catholics inevitably and increasingly set the tone for the Church, what is Catholicism in the 21st century going to be like? For one thing, Catholics in the global South—from bishops to clergy to laity—will seem to European and American eyes fairly traditional on matters of sexual morality and fairly progressive on just about everything else. On abortion, gay rights, gender roles, and the family, there is a consensus in the southern Catholic Church, as in southern cultures generally, that is markedly conservative. To see how that has played out so far in a different Christian context, consider the Anglican communion today, in which liberal Anglican churches in the United States, Great Britain, and Canada are pressing ahead with the blessing of same-sex unions and the ordination of openly gay bishops and meeting ferocious resistance from the Anglican constituency in the South, particularly in Africa. With 41 million of the 79 million Anglicans in the world now living in Africa (and with more practicing Anglicans living in Nigeria than in Great Britain), we can see which way the winds blow on these issues.

However, change the subject from culture wars to other issues—the ethics of free market global capitalism, war and peace, race relations, the environment, the arms race—and a consensus becomes apparent across southern Catholicism that by western standards seems liberal, and even progressive. (It bears noting, though, that this division of humanity into liberals and conservatives is a northern taxonomy. Such categories don’t occur to most people in the South.) Since the United States–led incursion into Iraq in March 2003, I have interviewed some 300 Catholic bishops in the South, and I have not found one who isn’t convinced that the invasion failed the Catholic Church’s tests for a just war.

Further complicating this picture is the fact that the ethos of Catholicism in the South is heavily biblical and supernatural. It is tied less to abstract scholastic theology and more to the Bible’s narrative universe and world-view, particularly the Old Testament and the Synoptic Gospels. Miracles, revelations, exorcisms, demonic combat—all of which in western culture can seem quaint or arcane or off-putting—are part of the routine of spiritual life in the South. The supernatural is close. People sense it. And they live in lively expectation that it is going to erupt in their daily experience.

This has practical consequences. How do you address health care, for instance, in a culture where the default interpretation of illness is not merely physical cause and effect but also the operation of malign spirits? Treating the physical source without attention to the spiritual realm in which healing must also take place will address only half the problem. Increasingly, the palpable nearness of the supernatural will be woven into the fabric of Catholicism in the 21st century.

Catholic leaders in the South see competition for souls arising from a different source than do their northern counterparts. In western Europe, and on the East Coast of the United States, we habitually think that the Church’s major competitor is secularism. But often in the South, you have to look hard to find a secularist. Secularism simply does not have a serious sociological footprint outside of the West. The reality in most of the world is the competitive dynamic of a flourishing religious marketplace. The typical Catholic bishop in sub-Saharan Africa, or in Southeast Asia, or in most of Latin America is worried about losing people to Christian Pentecostalism. In some parts of sub-Saharan Africa, new iterations of indigenous religions also raise concern. And in parts of India, militant nationalist Hinduism is a perceived threat.

Most people around the world do not choose between belief and disbelief. Rather, they shop for the particular brand of religion that suits them best. The Catholic Church in the South is not, in the main, fighting abstract intellectual battles. It is fighting pastoral battles. Southern bishops’ primary concern is that the Pentecostals are doing a better job of holding midweek prayer nights and organizing youth ministries. The focus of southern Catholicism for the foreseeable future is likely to be at this practical level.

According to the United Nations population division, 90 percent of the world’s people under 14 years of age live in the South. If there is one defining characteristic of southern Catholicism, that is it. I have been to eight countries in sub-Saharan Africa, and I have visited many a Catholic parish out in the bush. Most of the time, when you attend Sunday Mass in such places, you are not sure if you are in a church or a daycare center. Kids are literally hanging from the rafters.

Young people tend to inject a sense of optimism, a vision of the future taking shape. And so there is a shared outlook among southern Catholic leaders—among bishops and clergy, members of religious communities, theologians, and the laity. They are convinced that their historical time has come.

To appreciate the significance of this view, one need only compare the synod of African bishops convened in 1994 to the one that took place 15 years later, in October 2009. In 1994, the African bishops went to Rome essentially to get instructions from the home office. They returned last year in a markedly different spirit, aware of their role in the part of the world where the Church is growing most rapidly, and ready to engage in conversation about the Church’s future. There is now a determination in the global South to set the tone for the Church. The southern moment has arrived.

John L. Allen, Jr., is the Vatican correspondent for the National Catholic Reporter and author of The Future Church: How Ten Trends Are Revolutionizing the Catholic Church (2009). His essay is drawn from a talk he gave in Conte Forum May 5 sponsored by the Church in the 21st Century Center.