Professor Paul Lim's erudite analysis of the seventeenth-century debates over the doctrine of the Holy Trinity draws on a range of primary literature that is exceptionally adequate to the purpose, and enables him to contribute significantly to the historiography of the period. Lim shows how the protagonists reacted to each other, and contextualises them in relation to sixteenth-century English, and to European, attempts to defend or demolish the doctrine of the Trinity. By revealing the complexity of the debates, and by explaining the importance of scripture for all the protagonists, Lim warns anyone interested in the history of thought against facile connections: we should be wary, for example, of seeing Socinianism as an obvious precursor of the Enlightenment (pp. 18, 38, 67); we should not see ‘radical religion’ and ‘rational religion’ as polar opposites (p. 72). Theologians will be provoked by the people whom Lim discusses to ask questions that are remarkably contemporary, both about the Trinity and about other issues.

Lim's first chapter focuses on the anti-trinitarian theology of Paul Best and John Biddle, thereby introducing recurring themes. One concerns the reading of scripture. This is something of a leitmotif: Lim begins his Introduction by quoting Erasmus on the providential obscurity of scripture on the Trinity, and his final chapter, on the Gospel of John in early modern England, ends with Jacques Souverain's critique of that Gospel as affected by ‘Jewish wisdom speculation’ and Platonism – the inclusion of Souverain is one of the ways Lim provides a complete picture. Throughout the book we find anti- and pro-trinitarians appealing to the same texts, such as John 1:1; it is fascinating to see how, from Origen to the Jehovah's Witnesses, the use of θεος without the article has been taken as evidence against a co-equal Trinity. The controversies Lim analyses provoke us to ask for ourselves whether scripture is easy to interpret, or rather invites us to recognise it employs allegory and typology. Are we entitled to sit in judgment over scripture, and perhaps prefer Paul to John? In the light of our knowledge of first-century Judaism, should we see John as more Jewish than ‘Platonic’?

Another recurring theme involves the reading of the ante-Nicene Fathers and of the fourth-century Councils. The seventeenth-century debates invite many questions. Were the ante-Nicene Fathers ‘infected by Platonism’, or witnesses to a ‘simpler’ Christianity? Were they profoundly aware of the Trinity, and seeking to develop ways to expound that mystery; or was the doctrine a fourth-century innovation? Chapter 5 (‘Bishops Behaving Badly’) makes us ask whether it matters that councils that came to be recognised as ecumenical involved political manoeuvring, and by whose judgement other councils were not ‘received’ as authoritative.

Chapter 2 proposes the anti-trinitarian implications of ‘radical religion’. Lim shows that many defenders of orthodoxy saw Antinomianism and Socinianism as twin threats (pp. 75, 89). While admitting that the radicals were not Socinians (pp. 84–5), he argues that by almost identifying themselves as one of the Trinity, Ranters, Seekers and Muggletonians weakened the doctrine (p. 73). I am not fully convinced this follows. Lim recognises how the theme of theosis is present in the Cappadocians, Pseudo-Dionysius, Eckhart, Cusa and Calvin. In fact it is in the Jewish background to the New Testament (see Carl Mosser, ‘The Earliest Patristic Interpretations of Psalm 82, Jewish Antecedents, and the Origin of Christian Deification’, JTS 56 (2005), pp. 30–74); and participating in Christ's Sonship is important for Paul as well as for John. Augustine and Aquinas taught divinisation. It was a plank in the arsenal of Athanasius – and of the seventeenth-century Downame and Traheron whom Lim covers in chapter 6. Rejoicing in the privilege of participation in the divine nature through Christ seems more pro- than anti-trinitarian. John Turner's attack on ‘Mystick Theologues’ who claim to become ‘deify'd’, and Henry More's and Edward Leigh's more nuanced critiques of distorted claims to divinisation (pp. 98–100), are perhaps better taken as (justified) warnings against unbalanced spirituality than as ways of defending the Trinity.

In his third chapter Lim very helpfully explores the trinitarian reactions to Biddle, and in his fourth the ‘practical Trinitarianism’ of Francis Cheynell and John Owen. The latter theme finds echoes in the modern interest in the ethical and social implications of the Holy Trinity. Lim brings out how Cheynell's and Owen's divinity could be both polemical and practical. Despite the suggestion that ‘polity and theology’ were connected (p. 176), the word ‘practical’ as used here does not really involve aspects of ecclesial or social life. Instead, it points to liturgy and to devotion as it leads to character transformation – themes that certainly deserve attention in trinitarian theology.

Lim shows that some defenders of the Trinity feared Arminianism might slide into Socinianism (pp. 90, 176). But by presenting the Arminian Herbert Thorndike's attacks on Socinus and his followers, Lim paints a more complex picture (pp. 134–7, 171). Thorndike suspected that Socinus’ rejection of the Trinity was bound up with his rejection of an extreme Calvinist view of grace and of the ‘satisfaction of Christ’, a view he too rejected. Lim is properly sympathetic to the fear that denying the Trinity entails playing down Christ's satisfaction (pp. 46, 70–1), and hints that radical religion (which emphasised theosis) lost focus on the atonement (pp. 121–2). The kaleidoscope of positions Lim details reminds us that there is no necessary connection between a ‘low’ doctrine of our dependence on ‘operative grace’, and a rejection of the Trinity. It also prompts the question whether a robust doctrine of the Holy Trinity can go with a range of accounts of how Christ's sacrifice saves us.

The editors would have made the endnotes less troublesome by using ‘Notes to pages mm–nn’ as a running header. They could make this kind of book more accessible to the non-historian by including a table of the main protagonists analysed, giving their dates, affiliation and basic details, to save us having to look some of them up elsewhere. And they should prevent a computer turning Χ into Ξ, or putting into the Latin alphabet a word that is meant to appear in Greek (pp. 99, 280)! But such complaints are few. Lim has given us an admirably thorough and balanced analysis of the seventeen-century debates; he makes us reflect on the roles of reason, tradition and authority in interpreting scripture, wonder at the Socinian claim to complete the work of the Reformation by rejecting all three ‘T's (Transubstantiation, Tradition and Trinity), and ask afresh how the mystery of the Holy Trinity may be robustly preached and praised.