There is a story told about the alleged waning of Christianity that has been popular among secularists since the late 19th century. Grounded in the theories of Marx, Weber, Durkheim and Freud, and promulgated today by thinkers as varied as Peter Berger and Christopher Hitchens, the story maintains that from the time Christianity originated in the eastern Mediterranean until it reached its pinnacle of dominance in medieval Europe, it was sustained by populations longing to understand what their age simply could not, or did not wish to, explain to them.

The argument is that Christianity may have once served a purpose—motivating the masses, creating bonds between disparate members of society, placating psychological fears—but those days are gone. Modern science and technology have created alternative and far more compelling accounts of the workings of nature and the sources of life, death and healing, while growing urbanization has placed more and more people in a context where they rely on human, not supernatural, creations to sustain their everyday lives.

To the contemporary defenders of this account, Western Europe is the definitive proof case. Among the most educated and urban people on earth, Western Europeans have increasingly turned away from the practice of Christianity. According to some studies, on any given Sunday only 14 percent of Germans, 5 percent of Danes and 4 percent of Swedes and Finns attend church. As other regions of the world become increasingly educated and urbanized, the argument goes, Christianity’s decline will only hasten.

Of course, this now familiar story was modernity’s response to a much older and more deeply entrenched story—one that dates back to early church figures such as Tertullian and Augustine. In that competing account, demographic trends in Christianity do not foretell its demise but rather proclaim its truth. Founded by a small band of Jewish outsiders in an age of Roman dominance and persecuted to near extinction, Christianity quickly rose until by the fifth century it had become the ruling religion of the Roman Empire and later of all of Europe. How can one explain an ascension so sudden, so complete and so improbable except to trace it to the hand of God?

Contemporary proponents of this second view cite the fact that with 2 billion adherents, Christianity is still the largest religion in the world, and they point to the rapid spread of Christianity in the global South, especially in Africa, Latin America and South Asia. The Christian population of Africa numbered 10 million in 1900; by 2000, it had grown to 360 million. Over a similar period, South Korea’s Christian population grew from 300,000 to 12 million.

Mark Hutchinson, a professor of church history, writes: “What pundits thought was the death of the church in the 1960s through secularization was really its relocation and rebirth in the rest of the world.” In the face of violent 20th-century rebellions against Western colonialism in some of these very regions, the subsequent embrace of Christianity by the peoples of the global South has struck some observers as nothing short of miraculous.

Princeton University sociologist Robert Wuthnow steps into this debate with Boundless Faith. He is one of academia’s most respected and careful commentators on religious trends, and also one of its most evenhanded. On the basis of in-depth interviews with hundreds of church leaders and an extensive survey of American church members concerning their views of Chris tianity’s role in the world, Wuthnow debunks multiple myths about U.S. Christianity and globalization. He offers compelling reasons to question aspects of both of the popular accounts outlined above.

According to Wuthnow, globalization

affects the work of churches everywhere by advancing international networks, promoting communication, diminishing the boundaries separating nations and cultures, generating in some instances a corresponding backlash of nationalism and xenophobia, undermining the traditions and lifestyles of local communities, transferring power and wealth, fueling border conflicts, and creating large populations of refugees and immigrants.

Wuthnow contends that we do ourselves and others a great disservice when we attempt to summarize such a complex set of phenomena as simply good or bad, right or wrong—as signaling Chris tianity’s ultimate decline or its next triumph. It is better, Wuthnow suggests, to understand this revolutionary shift in the nature of Christianity than to polemicize about it.

There is little doubt that a seismic shift is occurring. According to the Center for the Study of Global Christianity, the demographic epicenter of the world’s Christian population has migrated from northern Italy in 1700 to central Spain in 1900 to central Africa today. At present, 28 percent of the world’s Christians live in Europe, 11 percent in North American and almost 60 percent in Africa, Asia or Latin America. The world in which missions from the Christian West set out to regions darkened by the hold of heathenism is no more. U.S. Christians traveling to Latin America or Africa are much more likely to find vibrant Christian communities with higher church attendance there than at home. As Philip Jenkins, author of The Next Christendom: The Coming of Global Christianity, has observed, Christianity’s spread southward is “one of the transforming moments in the history of religion worldwide.”

Wuthnow cautions us to avoid easy answers to questions about these shifts. To those who say that Christianity’s incredible growth in the global South is a sign of the work of the Christian God, he points out that much of the recent increase is simply due to exponential population growth in Africa, Asia and Latin America. In Ghana, for instance, “growth in the Christian population during the 1990s was 95 percent from natural increase and only 5 percent from conversions.” Wuthnow also reminds us that for all of Christianity’s gains in raw numbers of adherents, Islam has grown much more as a percentage of the world’s population.

To those who cite a new phenomenon of “foreign missionaries” coming to the U.S. from the global South, Wuthnow also advises caution. One recent study claimed that 33,000 missionaries from churches in Africa, Asia and Latin America were working in the U.S. as of 2000. Jenkins cites a current South-to-North missionary push, even going so far as to compare it to Catholic efforts to convert parts of Protestant Europe during the Counter-Reformation. Wuthnow has a simpler theory: the 33,000 foreign missionaries said to be working in the U.S. may simply be “immigrant pastors ministering to immigrant populations.” These individuals may have little impact on Americans beyond their own immigrant communities. It is not that Wuthnow holds the phenomenon to be unimportant—it is significant that Christians from overseas are serving immigrant populations in the U.S. with pastors born and trained in their home countries. The question is whether this situation is different from what happened when large numbers of Greek, Irish, Polish and other immigrants came to the U.S. in the first half of the 20th century and set up churches in which their own languages were spoken and that were led by homegrown pastors.

For the argument that evangelicals strongly influence U.S. foreign policy while mainline Protestants sit passively in the background, Wuthnow finds little supporting evidence. The evangelical leaders he interviewed often took credit for “groundbreaking human rights initiatives,” especially with reference to the policies of the Bush administration. “Yet it is unclear that evangelical Protestants were actually the earliest or the most ardent proponents of international human rights,” Wuthnow contends. Instead, he traces a longer and more consistent defense of human rights coming from organizations such as the National Council of Churches and suggests that in the slow-moving arena of national policy, these quiet but steady efforts may have more influence than personal and fleeting connections to the Oval Office.

Mostly, Wuthnow’s interviews revealed that U.S. Christians—evangelical and mainline alike—are skeptical, even cynical, about the influence they have on U.S. foreign policy decisions. As one Salvation Army leader observed, “Government policies are much more driven by what’s best for the U.S. economically than anything else. It may be phrased differently by who’s in office, but the bottom line is self-preservation.”

Finally, Wuthnow challenges the claim that U.S. Christianity’s global influence is in decline. The Internet and advances in telecommunications have made the world smaller, and U.S. Christians have the financial resources and organizational structures to make full use of these tools—and a growing inclination to do so. “There are more American missionaries, more faith-based humanitarian and relief workers, and more short-term volunteers serving abroad than in the past,” Wuthnow reports. Fifty-seven percent of churches with at least 1,000 members reported that their church had sent some of their members overseas on a mission trip in the past year. Mainline Protestant denominations in the U.S. now employ 22,000 full-time staff dedicated to supporting international missions—up 50 percent in the past decade—and an additional 600,000 individuals serve as part-time volunteers.

Young Christians are particularly likely to participate in mission work abroad. Of current churchgoers who were active members of youth groups during the past decade, 12 percent reported that they had gone overseas on a mission. Twenty years ago, that number stood at 2 percent. All evidence suggests that such experiences are life-changing. One individual recalled what he learned during a mission trip that he made to Mexico when he was 18: “This is what the world is really like. We live in a bubble in the United States and don’t know the intensity and struggles of life almost everywhere else in the world.” Another, who had worked with AIDS orphans in Zambia, observed, “You’d have to be dead in the soul not to be moved by what’s happening there.”

The influence of U.S. Christianity in the world thus remains strong and may well be growing. But how should it be directed? Should U.S. Christians “serve the world” simply by evangelizing others, or are Christians also charged to work to cure AIDS and to stamp out political oppression? Now that a significant number of Christians can be found in every region of the world, should U.S. Christians continue to see themselves as missionaries to the world, or should they be partners with Christians indigenous to the areas being served? What does it mean to be genuine partners with Christians who may have very different perceptions of the world and of the faith? How is U.S. Christianity itself being transformed by new, complex and multifaceted interactions with people of the global South?

Wuthnow’s clear and systematic discussion of a topic that has too often been dominated by polemics brings these questions to the forefront. How U.S. Christians answer them in the years ahead will influence the future not only of Christianity but also of the globe.