Baird Tipson's book intervenes on a long-standing question: how does Evangelicalism relate to Protestantism? More specifically, how do you get from the sixteenth-century Reformation to the revival theology of the eighteenth century? Tipson's answer centres on the development of Protestant understandings of baptism and conversion. Beginning with late medieval indulgences and Luther's critique of the same, he goes on a theological tour through early Reformed and Lutheran disagreements, sixteenth- and seventeenth-century Puritan and Anglican divines, and finally the ‘new birth’ theology of the eighteenth-century revivalists. Along the way, he argues that within Luther's theology was a seed which inevitably grew into the Evangelical emphasis on interior experience. ‘If you start with a Luther’, Tipson summarises, ‘sooner or later you are bound to get a Wesley’(p. 2). If the book does not fully explain the emergence of Evangelical theology, it offers an insightful account of the development of a doctrinal and pastoral question that Protestants had to answer.

This question can be put simply: if the efficacy of baptism depends on the recipient's faith, how might one know they have saving faith? In his first two chapters, Tipson explains how this question arose from Luther's rejection of the late-medieval theological system in which Christians received converting grace through the external sacraments of baptism and penance. By the time of the writing of the 1529 Large Catechism, Luther's thought held two emphases in tension: on the one hand, he insisted on the strength and efficacy of baptism; on the other, he taught that without faith, baptism was useless. Chapter iii outlines how the next generation of Protestant theologians diverged: Lutheran theologians such as Jacob Andreae stressed that baptism was an efficacious sign of God's promise to grant the gift of faith, while the Reformed Theodore Beza picked up on Luther's emphasis on the importance of subjective faith. Beza's prioritisation of inward baptism, Tipson argues, was the theological move that ‘would eventually make evangelicalism possible’ (p. 8).

The remainder of the book follows the trajectory of Beza's thought. Chapter iv explains the ‘conscience religion’ of Puritan theologian William Perkins, who warned readers not to trust in their baptism, but rather examine their conscience for evidence of an inward baptism. Chapter v considers three seventeenth-century Richards: the Puritan Baxter, who responded to Antinomianism by preaching the need for rigorous self-examination of conscience; the Restoration churchman Alestree, who ignored conversion and called Christians to dutiful observance of God's commands; and the nonconformist Alleine, whose terrifying sermons on damnation hoped to convert listeners from ‘self-will’ to a life of strict obedience to God's governance (p. 137).

The sixth chapter brings home the argument. Tipson shows how George Whitefield, John Wesley and Jonathan Edwards rejected the moralising approaches of the prior century, prioritising inward baptism as had Perkins and Beza. But Wesley and Whitefield, unlike the Puritans, emphasised the immediate perceptibility of the new birth – they preached that the Holy Spirit directly revealed one's conversion. Edwards's account was subtler: rather than immediate communication, the Spirit granted the converted a spiritual sense that enabled them to intuit their love for God. In all three the Puritan model of conscience religion was supplanted by ‘a decisive, perceptible experience of conversion’ (p. 172). Tipson concludes that once Protestants prioritised inward baptism, eventually they had to explain how the Christian knows s/he is inwardly baptised: ‘Making the efficacy of a sacrament depend upon the faith of the participant was going to lead to efforts to determine the authenticity of that faith’ (p. 174).

This two-and-a-half-century survey is largely persuasive. Tipson shows continuities from Luther, through the Puritans, to the Evangelical new birth. The chapter on William Perkins is especially strong. Even those readers well-versed in Puritan thought will benefit from the detailed treatment of the sixteenth-century theologian and his influence. More generally, the book's attention to a particular doctrinal loci, and one that was clearly of pastoral and experiential significance, works to illuminate a trajectory that eventually played out in Evangelical revivalism. Each theological episode in this story becomes more interesting because the reader encounters what came before and after.

Inward baptism makes a deliberately narrow contribution, and Tipson is careful to point out that other historians have explained the when, where and how of early Evangelical revivalism. The book is less about the emergence of Evangelicalism, and more a genealogy of one aspect of Evangelical theology. However, even within this limited focus, the emphasis on an inexorable progression may neglect contingencies. In particular, did ‘inward’ mean the same thing in the eighteenth century as in the sixteenth? To what extent was ‘the self’ an emerging rather than stable notion in the early modern Anglophone world? Engaging with Bruce Hindmarsh's work on conversion might have added useful intellectual and cultural context to this account of the Evangelical new birth. Development, after all, is not the same as inevitability.

And, while High Anglican and Pietist theologies make their appearance, Inward baptism is largely a story about the antecedents and outcomes of Puritanism. The weight of the argument, and the bulk of the book, is on the connection between Puritan and Evangelical accounts of saving faith and conversion – thus the attention given to Douglas Winiarski's argument in an appendix. In particular, Continental Pietism plays little part in this story, a notable difference between Inward baptism and recent accounts by Mark Noll, W. R. Ward and Thomas S. Kidd, each of whom treats Pietism as central to early Evangelical spirituality. How would adding the Pietists confirm or complicate Tipson's inevitability thesis?

These questions are meant only to clarify the kind of contribution the book makes. By giving sustained attention to a single theological concern, Tipson offers us a longue durée of Protestant conversionism. Even if specialists might quibble on particular points, they will benefit from the book's breadth and careful parsing of Puritan theology. Inward baptism would be useful in classes on historical theology or religious history and should be read by anyone interested in the history of Protestant doctrine.