This is a welcome contribution to a growing body of work on what Nathan Jacobs and Chris Firestone have termed ‘The persistence of the sacred in modern thought’. Other examples would include the work of the philosopher Maria Rosa Antognazza and the political scientist Michael Allen Gillespie, whose Theological origins of modernity (2008) defines the genre. The myth of the secular Enlightenment is one that mistakes heterodoxy for atheism or, in one influential case, ‘the rise of modern paganism’, and it relies excessively on the polemical utterances of orthodox theology. To take the most obvious examples: theologians brand Hobbes and Spinoza as atheists, and scholars mistake the insult for a historical judgment.

Jonathan Birch exposes the fallacy with relentless erudition in this fine volume, revealing the strange kinship between the exultant narrative of a secular Enlightenment, extolled by authors such as Anthony Pagden and Jonathan Israel, and the rogues’ gallery of godless and presumptuous secularists that emerges from evangelical writers such as N. T. Wright. Hobbes’s contention that religious faith is rooted in fear, for example, was not the withering reductionism that it has often been taken to be. It was a simple inference from the Proverb that ‘the fear of the Lord is the beginning of wisdom’. Generations have been taught to think of the eighteenth century as a time of Promethean revolt. But it was not God, still less Jesus, that the radicals and philosophers rejected: it was Duns Scotus, John Calvin and Augustine of Hippo.

We know already how equality and liberty drew on the heresies of the Quakers and the Levellers, and how the Fourth Gospel became a gospel of dissent, in which the inner light of Christ became a source and model for a radical and fissiparous reason, but Birch shows us how the very notion of free will drew on the philosophia Christi – the solid ground of rational choice – with which Erasmus of Rotterdam confronted the deracinated voluntarism of Martin Luther. How do we know that humans are capable of making decisions? How do we know that we are not bouncing around in an empty game of chance, played by an imperious and inscrutable God? wonders Erasmus. Jesus is the guide out of the ‘voluntarist’ labyrinth – that is, the impregnable fatalism of those medieval scholars who held that divine will is impervious to human reason. This was a theology that could lead individuals to despair and fix tyrants to their thrones and it is the figure of Jesus, quite as much as any spiritualist intuition, that pulls the edifice down to earth. Much of the Enlightenment’s rationalism, Birch demonstrates, is akin to Thomas Aquinas’s project of studying theology in a spirit of expectation that human groping and divine will may be ultimately relatable. This is where the book excels, showing how epistemology – the very confidence to ask and know – is anchored either to faith or the historical figure of Jesus. In that respect, it bears some comparison with Peter Harrison’s work on theology and the foundations of science. A perfect illustration of his thesis is a quotation from the Dutch jurist Hugo Grotius: ‘Measureless as is the power of God, nevertheless it can be said just that there are certain things over which that power does not extend … Just as even God, then, cannot cause that two times two should not make four, so He cannot cause that which is intrinsically evil be not evil.’ This, notes Birch, is a classically Thomist stance – against the voluntarism of Luther and Calvin. It is not the birth of an autonomous reason.

We meet the radical and feminist Jesus, through the Quakers Margaret Fox and James Naylor, the mystical and cosmopolitan Jesus, in Spinoza, and the political (or apolitical) Jesus, whose defiant poise before Pontius Pilate convinced Thomas Hobbes of the need to separate Church and State. We meet the republican Jesus, who said that only the Gentiles lord it over their people, and that his disciples would be different, and we meet the tolerant Messiah who said that where two or three are gathered in his name, there he would be. This verse, from the Gospel of Matthew, was quoted with delight by John Locke, against those who denied the authenticity of unorthodox sects of the late seventeenth century. This statement attributed to Jesus, noted Locke, ‘seems to imply the contrary’ of the view that no sect or Christian society ‘can be said to be a true Church unless it have in it a Bishop or Presbyter’. Not to mention the fact that love or charity would lean on the side of toleration, rather than force. ‘If’, advised Locke in his influential Letter concerning toleration,

This was John Locke, the architect of the social contract and the liberal state. These are just a handful of examples from a book loaded with new perspectives on this age of reason and doubt. To paraphrase the Kantian paradox at the heart of this study: Was the Enlightenment a Christian movement? No, but it was an age of faith.