Judith Shulevitz wants to know why conservative churches are strong and growing. Writing in the May 12, 2005 edition of Slate, Shulevitz shares the confusion of many on the secular left in wondering why strict religious movements appear to be growing while more liberal movements decline.

In recent months, many observers have awakened to the fact that conservative Christianity is a major force in America. Driven by basically secular assumptions, most seem to assume that this phenomenon should be explained by sociological or psychological factors. As Shulevitz acknowledges, the kind of piety and conviction commonly found among evangelicals “is often dismissed as a social pathology.”

In her article, “The Power of the Mustard Seed,” Shulevitz considers groups beyond conservative Christianity. Nevertheless, the main thrust of her argument is that conservative churches draw strength from the very strictness of their beliefs and practices, whereas more liberal groups dissipate through lowered rates of involvement and diminished truth claims.

Drawing on a significant body of sociological analysis, Shulevitz suggests that what the economists call “rational choice theory” may be the best explanation for the strength of conservative churches. According to this economic theory, individuals act as “rational agents” who make decisions on the basis of self-interest. In other words, persons join conservative churches because they believe such membership to be in their best interests.

In setting forth her case, Shulevitz draws on research conducted by sociologist Laurence R. Iannaccone of Santa Clara University. Iannaccone published an influential essay, “Why Strict Churches Are Strong,” that was published in the American Journal of Sociology in 1994. Iannaccone was convinced that rational choice theory does explain the relative strength of conservative denominations and the corresponding weakness of more liberal churches. Iannaccone’s research was also a reconsideration of the theories of Dean Kelley, whose 1972 book, Why Conservative Churches Are Growing, set the stage for later debate.

Following Kelley’s lead, Iannaccone argued that “strictness” is the clearest indicator of congregational strength and potential for growth. He defines strictness in terms of “complete loyalty, unwavering belief, and rigid adherence to a distinctive lifestyle.” Thus, the churches that require members to hold definite doctrinal beliefs and to share common moral commitments are more likely to grow and remain strong than churches who have lower expectations in terms of both belief and behavior.

Refuting those researchers who argue that the growth of conservative churches is due to demographic factors, birth rates, and socioeconomic conditions, Iannaccone suggests that doctrinal and behavioral strictness “increases commitment, raises levels of participation, and enables a group to offer more benefits to current and potential members.” Thus, these groups are able to “enjoy a competitive advantage over their opposites (who suffer from less commitment, lower participation, and fewer perceived benefits).”

How does this work? Iannaccone explains that “Strict churches proclaim an exclusive truth–a closed, comprehensive and eternal doctrine. They demand adherence to a distinctive faith, morality, and lifestyle. They condemn deviants, shun dissenters, and repudiate the outside world.” In other words, the strictness of these congregations comes down to a set of common theological and behavioral expectations and commitments.

In a fascinating analysis, Iannaccone argues that the very strictness of these groups largely eliminates what economists and sociologists call the “free-rider” problem.

Free-riders are, according to this sociological analysis, those who wish to identify with a group without accepting any high level of demand. Conservative churches have few free-riders because the high levels of conviction and counter-cultural moral standards raise the cost of membership above what free-riders are willing to pay. More liberal churches, on the other hand, are more likely to accept as members those who both believe and behave in ways that would be unacceptable in more conservative churches. Iannaccone’s sociological analysis leads him to believe that liberal Protestantism–especially as represented in the so-called “mainline” denominations–suffers from a significant free-rider problem that has led to pervasive weakness.

Iannaccone’s rational choice theory analysis clearly contains a large element of truth. After all, it just makes sense that churches marked by higher expectations of behavior and more demanding beliefs are less likely to attract persons of mild to moderate commitment. In the context of postmodern America, members of conservative churches have found themselves out of step with the larger culture and, in sociological terms, to be paying a higher price for their commitments. Can a church be too strict? Iannaccone clearly believes so, and argues that churches given to extreme eccentricities can suffer from a backlash.

Kelley, Iannaccone, and Shulevitz want to explain the strength of conservative churches in largely sociological terms. Of the three, only Kelley seems to understand that deeper theological issues are at stake. After all, why would members of conservative churches be willing to pay such a high price for membership if there is no compelling reason to do so? This is where rational choice theory runs into a direct collision with theology.

A more comprehensive analysis has been offered by researchers Dean R. Hoge, Benton Johnson, and Donald A. Luidens, who conducted a major research project directed at churches affiliated with mainline Protestant denominations. Their work, Vanishing Boundaries: The Religion of Mainline Protestant Baby Boomers, acknowledges that the basic dynamic behind church growth and decline is theological rather than sociological or economic.

These researchers argue that the most important factor making churches strong is “the presence of a compelling teaching concerning the ultimate purpose and destiny of humankind.” Dean Kelley identified this “compelling teaching” as “meanings.” These meanings make demands upon believers, and these believers are far more likely to congregate together, rather than to join more liberal churches. Holding to strong beliefs, conservative Christians are less likely to accept weaker beliefs as being equally valid.

Hoge, Johnson, and Luidens are clear: “Our findings show that belief is the single best predictor of church participation, but it is orthodox Christian belief, and not the tenets of lay liberalism, that impels people to be involved in church.”

When these researchers speak of “lay liberalism,” they refer to a phenomenon they observed among mainline baby boomers, whose vision of Christianity involves very few definite beliefs or moral obligations. “Although lay liberalism has several different versions,” they explain, “its defining feature is the rejection of the claim that Christianity, or any other faith, is the only true religion. Lay liberals have no compelling truth, no ‘good news,’ to proclaim, and few of them share the views that they do have with their friends and acquaintances.”

Judith Shulevitz suggests that liberal denominations should look to this body of research and modify themselves so that their members will find deeper meaning and connection. Her answer is a recovery of ritual. Nevertheless, her concept of ritual has no specific theological content. As she argues, “the greatest religious leaders have understood [that] ritual is theater. You can use it to send any message you want.”

In other words, she missed the point entirely. Laurence Iannaccone’s rational choice theory can actually explain very little about conservative Christianity. Hoge, Johnson, and Luidens offer a much more substantial and accurate analysis. The fundamental issues are theological, not sociological. Evangelicals are willing to pay a high social cost for the Christian faith, precisely because we believe the Gospel to be true. Furthermore, Christians know better than to expect fulfillment in this world. True satisfaction will be realized only in the age to come, and a perspective focused on eternity transforms the questions of everyday life.

Just consider the apostle Paul. Writing to the Philippian Christians, Paul asserted, “For to me, to live is Christ and to die is gain.” That, more than anything else, explains why churches that believe and teach the Gospel are growing, and why those who have abandoned the Gospel are dying.