Kling begins his massively erudite and readable study with the story of his father's conversion to evangelical Christianity experienced—a story that, as Kling explains, fits within a particular form of “believers’ church” or evangelical Christianity that for the past 250 years has enabled millions of people to experience “a crisis moment of ‘new birth,’ often chartable, datable, and memorable” (6). The lesson Kling draws is that his father's experience of conversion was dependent in significant ways upon the particular form of “Christianity” that his father encountered. As he put it, “The way in which conversion occurs and is expressed illumines the distinctive characteristics of Christianity in any given period” (xi).
Pages 27 through 200 examine conversion from the New Testament through the year 1500. Kling shows that, beginning in the patristic period, entrance into the monastic life came to be seen as a form of Christian conversion, as the believer sought a deeper configuration to Christ. In the late twelfth and early thirteenth centuries, the rise of nonmonastic religious orders such as the Franciscans and Dominicans redefined conversion to mean the active evangelization of others. Late medieval piety emphasized conversion as spiritual renewal, available to monastics and laity alike. In this necessarily brief history, we find some unsavory episodes, such as the ninth-century ruler of Bulgaria converting to Orthodoxy after surrendering to a Byzantine military force. This same ruler toyed with converting to Roman Catholicism, only to be stopped by a forceful anti-Roman-Catholic campaign by Photius, Patriarch of Constantinople. Photius convened a synod that condemned Pope Nicholas I and various teachings of the Roman Catholic Church, most notably the filioque. This episode helped to produce the Great Schism of 1054. Kling concludes, “What sweetened the deal for Boris and dissuaded him from making any more overtures to Rome, despite Rome's persistent attempts in the next decade to bring Bulgaria back into its fold, was the grant of a separate archbishopric. If not for his courting of Rome, the council probably would not have permitted an autocephalous diocese” (146).
Kling also includes a lengthy section on Christian persecution of Jewish communities, which led to few conversions and more notably involved such things as a mid-thirteenth-century “trial of the Talmud that culminated in the public burning of twenty-four wagonloads (10,000 to 12,000 volumes) of priceless Jewish manuscripts” (159). Horrific episodes such as these proved the resiliency of Judaism against Christian pressure.
The bulk of the book (pages 203–660) covers the 500 years since the onset of the Reformation. In Kling's view, the impulse to separate the truly converted from their false brethren—including many more or less corrupt souls who wielded ecclesiastical power in the period 1350–1517—helped to bring about the Protestant Reformation. In the end, as he says, the sixteenth-century “reformers became convinced that an irreversible and uncompromising conversion from the falsehoods propagated by the Church to the truth of the gospel was necessary before ecclesiastical reform could occur” (205).
Kling pays significant attention to India, with some fascinating details about how in certain cases “Hindu reform societies played a crucial role in bridging the vast theological chasm between Hinduism and Christianity” (533). The history of Christianity in China receives even more attention. Kling demonstrates the fruitfulness in recent years of “‘black-market’ underground churches” (513) for attracting converts. He explores the reasons for the rapid growth of Latin American Pentecostalism in the 1980s and 1990s. He shows that evangelicalism often succeeds by joining central Christian doctrines to real and positive changes in lifestyle. He also provides lengthy sections on many other topics, including (for instance) European Catholicism and Protestantism, the seventeenth- and eighteenth-century Jesuit missions in America, the Puritans and the Great Awakening, and African American conversions under the slave system.
Although recognizing the ugliness of coercive evangelization, Kling notes that person-to-person evangelization is frequently a sincere work of love on the part of the evangelizer. He bears witness to the transformative power of conversion in many Christian lives. At the same time, he shows what an often-dismal mixed bag Christian history is, like all human history.
