The relationship between conservatism and American politics is one of paradox and strain. The founding documents of the American nation preach equality, freedom and universal, inalienable rights. The American polity is and was nothing less than a protest against hierarchies of blood and birth: the innateness of the Old World. With such values, Protestantism holds many affinities. Indeed some would argue that the Reformation all but created them. American conservatism, on the other hand, has tended to sacralise hierarchy and the established social order, and it has done so in the name of the political tradition that declared war on hierarchy. American conservatism is a religion of priests wielding the words of the prophets – an awkward mix. Such is the tension explored in Protestants and American conservatism.

The story begins in the colonies, where a foundation for American conservatism was laid in the organic theocratic polities of New England: Christian Commonwealths. Theocracy meant that only full church members were able to vote or hold public office. It also meant rigor, discipline and control. The Massachusetts Bay Colony attempted to curb drinking by forbidding people from drinking toasts to one another (p. 17). The Puritans’ conservatism was, as Harp suggests, more consistent than later forms. It was based on hierarchy, indeed ‘a robust affirmation of human inequality’, a principle established in the depths of Puritan theology. This applied within the community – to differences of social station – and between the colonies and their neighbours. Catholics, Anglicans, Indians, Spanish, French: each occupied lower places in the divine scheme. This ‘particularist Christian vision’ was bound to conflict with the universalism of the radical Protestant and natural rights traditions, which underscored the doctrines of the American Revolution, and it did.

It was, said John Quincy Adams, the ‘highest glory of the American Revolution’ that it united the principles of Christianity with the principles of civil government. But, in truth, John Locke and John Winthrop were at war. Puritan philosophy wanted to stand athwart history and shout ‘Stop!’ long before it became fashionable to do so. And however firmly rooted in Christian ideas of creation, human dignity and collective charity, the Lockean concept of ‘social contract’ always struck the more communitarian and conservative strands of American thought as abstract and ahistorical. This was perhaps the heart of the tension between American conservatism and the republican political tradition. Republicanism, in its purest or boldest formulations, celebrates the person not the place where he or she was born: it is universal, not patriotic; it honours humanity not the Englishman or the American, and it will not make exceptions. Its highest values are the rule of law, equality before the law, transparency and accountability. Yet these are not ideas that will win wars against a naval superpower of the eighteenth century; in fact, they are not the stuff of revolutions at all. So the American revolution was not the glorious union of Christianity, patriotism and civil government that John Quincy Adams believed. It was an explosive alliance, even a marriage of convenience, between a set of sober republican principles and an incipient and inchoate patriotism. In the decades after the Revolution, patriotism would pull America into European, almost monarchical, behaviours. The republican tradition would try to steer her away from militarism, wars and doctrines of hierarchy. Patriotism arguably won – meaning that American conservatism embodied values that tore at the seams of the American polity. The most obvious of these was of course slavery in the antebellum South. But the tension was also apparent in the Romantic and organic philosophies of Northern intellectuals, such as Horace Bushnell. Much of Harp's story concerns nineteenth-century thinkers who explicitly repudiated the Lockean principles of equality and social contract as godless inventions, declaring instead that government and social order are divine instruments. Thomas Jefferson's reluctance to believe that God had ever ‘chosen’ any particular people or nation for his own was, as Harp notes, almost enough to doom his presidential ambitions in 1800. Jefferson who said that all were created equal was stigmatised for ‘his uncertainty about whether God had ever designated one nation his chosen people’, writes the author (p. 66). Almost everything in this engaging study could be interpreted within these poles of equality and chosenness: the God who cares for all, and the God who has favourites. Christian nationalism, it seems superfluous to note, is a central feature of this drama. Christian patriots were often condemning ideas that were both Christian in origin and foundational to the American Constitution, while sanctifying hierarchies that appeared to contradict both. Harp's discussion of the conservative movement's embrace of the ‘free market’ in the Gilded Age is one of the highlights of the volume, and one that sets the scene for his analysis of a twentieth-century Christian conservatism as largely secular. Franklin Delano Roosevelt's withering response to Christian hostility to his New Deal policies captures the essence of this critique. The gospel of the free market, said Roosevelt, was that ‘you shall love God and then forget your neighbor’ (p.156).

It is, however, the crashing Manicheanism of the Christian Right as it emerged in the 1970s that draws Harp's sharpest judgements. Activist Evangelicals of the Jerry Falwell stamp, argues Harp, were driven by a ‘revanchist ideology’ that was shaped more by slogans and the ‘secular categories’ of anticommunism, militarism and market forces than Christian theology (p. 235). Fighting to preserve the status of the Bible and corporate prayer in the public schools, their approach to Scripture was, he contends, driven by proof texts and superficial analysis. One of the reasons Evangelicals made common cause with non-Evangelical Republican politicians, from Barry Goldwater to Newt Gingrich, was this bedrock of anti-Communism and economic individualism. While fighting for the Bible, politicised Evangelicals essentially neglected it, developing a political philosophy detached and at times divorced from the tradition's moral and intellectual resources. So it was not so much that Evangelicals were ‘played’ by Richard Nixon and Ronald Reagan: they were playing the same game. And the game, the blood sport of adversarial politics, moulded them more than they knew.

Evangelicals of the 1980s and ’90s, laments Harp, knew nothing of the ironies of history, taught by Reinhold Niebuhr, or dialectics of Christ and Culture explored by Abraham Kuyper. Their voices were loud but their thinking was thin. I am not convinced that the contrast the author draws between these modern Evangelicals and their more learned forebears is as clean and decisive as he claims. But his analysis of a movement that would help to deliver Donald Trump to the White House in 2016 is penetrating. What, asked journalists, do Christian zealots and a bombastic real estate tycoon have in common? More than you would think, suggests this thoughtful and challenging study.