David Kling's prodigious volume, The History of Christian Conversion, attempts to tackle two basic questions: What does Christian conversion mean? And why do people convert to Christianity? Kling notes that some approach these questions from an evangelical perspective, thinking of conversion as a sudden, individualistic change of the heart. Others, however, perceive the notion of conversion negatively, either as an act of coercion or as an example of triumphalist colonialization. Instead, Kling offers a more nuanced, if more modest, thesis: “the way in which conversion occurs and is expressed illumines the distinctive characteristics of Christianity in any given period” (xi). Using Lewis Rambo's sevenfold “typology of conversion” but also other models of conversion theory (including William James, A. D. Nock, Ramsay MacMullen, and Lane Fox), Kling attempts to explore a variety of conversion motifs: intellectual, mystical, experimental, affectional, revivalist, and coercive. Instead of privileging one form of conversion over another, Kling's work promises to explore a wide array of conversion “themes” throughout Christian history and across the globe.

Part 1, “The Roman World,” covers the first through the late fourth century. Kling examines both New Testament accounts and early Christian thinkers (e.g., Justin Martyr, Cyprian, and Constantine) to identify a variety of reasons for Christian conversion: a sense of the divine, communal belonging, the promise of moral transformation, intellectual attraction, the example of martyrs, and strong leadership. Kling rightly concludes that “no single model of conversion predominated or defined Christianity in the first three centuries” (77). The post-Constantine period, however, marks a shift in conversion. Once Christianity became the privileged religion of the empire, motivations for conversion changed, and religious syncretism became more prominent, raising new questions about the meaning of conversion.

In part 2, Kling explores the thousand-year period of early medieval Europe (500–1500), including the thorny question of the coercive “conversion” of Jews and pagans. In this section, Kling also argues for a distinction between the “Christianization” of a culture and “conversion” itself. Yet, here the argument lacks clarity and at times contradicts itself. On the one hand, Kling favorably observes that “conversion was not a warming of the heart, but a change of public practice” (104); yet, on the other hand, Kling argues that examples of public, cultural change in the family, politics, and material artifacts (e.g., baptisteries and inscriptions) are, in fact, not evidence of conversion, only “Christianization.” Later on, however, Kling will use material evidence of graves and prayer inscriptions in Scandinavia to argue for a “definite conversion to Christianity” (142). Further clarification on the relationship between Christianization and conversion would be helpful here.

In part 3, “Early Modern Europe,” Kling analyzes the experience and themes of conversion in the Protestant Reformation, European Catholicism, and in the rise of Evangelicalism. Contrasting Reformation and Catholic thinkers, Kling helpfully demonstrates that both groups were borrowing preexisting medieval notions of conversion (renewed spiritual commitment and inner birth); yet, Protestants (e.g., Calvin, Luther, and the Puritans) called for a “change of institutional commitment” (226), while Catholic thinkers (e.g., Ignatius of Loyola and Teresa of Avila) stressed “continuity, not disjunction” with existing ecclesiastical structures (233). Additionally, Kling's treatment of seventeenth- and eighteenth-century Evangelicalism in Germany and England cogently argues that this period produced “a new understanding of the self” (321), marking a historical shift that emphasized conversion largely in individualistic terms.

The remainder of the book explores conversion through a geographical survey. Part 4, “The Americas,” examines Catholic missions in America (e.g., de Las Casas), the American colonial period (e.g., Jonathan Edwards), and the various historical revival movements from the First Great Awakening to Billy Graham. Kling helpfully identifies the variety and complexity of conversions throughout these periods, as well as the questions of conversion as identity and transformation versus cultural replacement or obliteration.

In part 5, Kling turns to the spread of Christianity in China. Through an examination of Jesuit missions (e.g., Matteo Ricci) and Protestant evangelistic efforts (e.g., Hudson Taylor and the China Inland Mission), Kling attempts to analyze conversion in light of the complex relationship between Christianity and Chinese indigenous religions. Unfortunately, while Kling successfully shows the variety of Christian missionary strategies in China, this section reads more like a social-scientific survey of Christian growth in China, rather than a careful examination of the specific question of conversion itself.

Part 6, “India,” contrasts the themes of conversion in upper-caste and lower-caste India. In particular, this section addresses the fascinating interplay between Christianity and Indian (primarily Hindu) religion and culture through a process Kling terms the “Indianization of Christianity” (537). This reviewer was surprised, however, that Kling provides no discussion of St. Teresa of Calcutta's mission to the poor or the ministry of Lesslie Newbigin, whose writings on conversion are often considered some of the most important theological reflections on the topic in the twentieth century.

Finally, in part 7, Kling surveys modern Christian conversion on the African continent. This section offers a particularly insightful discussion of the troubling question of conversion as triumphalist “colonialization.” Kling persuasively demonstrates that such a view, though common, is “fraught with the problematical assumption of the unidirectional, hegemonic impact of missionaries on the African people,” and thus deprives Africans “of any independent will or agency” (584–585). As in his section on India, Kling offers compelling examples of the “Africanization of Christianity” through the indigenous work of William Wadé Harris in West Africa and in the East African Revival movements.

A concluding chapter helpfully restates Kling's thesis that Christian conversion is “a multifaceted phenomenon” (669), containing a variety of themes and motifs, none of which should be considered the dominant or preferred experience. In the end, despite the critiques above, Kling's work successfully helps the reader better understand both the complexity and the unity of the conversion experience over two thousand years of Christian history. Future discussions of the question of Christian conversion will most certainly need to engage with Kling's work.