What is the role of religion in the public square? This question has bedevilled political thinkers and theologians for centuries. In Western politics and culture, the debate began in early modern Europe, when the Reformation undermined the position of the Roman Catholic Church and the wars of religion ended with the functional separation of church and state – and more precisely, with the state ascendant at the long-term expense of the church. Since World War II, the debate over religion's place in public life has been especially vigorous in the United States, despite the official separation of church and state, because American religion has retained a popular salience and vibrancy missing in Canada and Europe. Indeed, in a society as religiously pluralistic as America, one might even argue that the First Amendment's separation of church and state has made the issue even more difficult to solve. Canadians and Europeans debate religion's role episodically, briefly, and mostly superficially because the majority of people are simply not that religious. When such problems do arise, they almost invariably involve the function of faith among immigrant populations (such as whether to permit the use of Islamic sharia law) or ethical questions involving the sanctity of life (such as abortion) that have prevailing ethical dimensions now largely independent of religion.

In the United States, the past three decades have witnessed two trends that, on the surface, contradict one another: the rise of conservative Christianity and the increasing secularization of culture. What their simultaneity points to, of course, is the dominance of neither but instead the deepening polarization of American life. Due to the strength of Republican politics since the 1970s, conservative Christianity has also prospered and gained an influential political role. This development in turn has frightened and angered liberals, both religious and political. Yet the steady erosion of religious values within American culture at large has led to fears of religion's decline among conservative Christians. Thus both liberals and conservatives have expressed concerns about the place of religion in the public square, albeit from starkly different perspectives which draw radically different conclusions: liberals want less religion, conservatives want more.

In tackling America's religion problem, two new books – Vincent Rougeau's Christians in the American Empire and R. Marie Griffith and Melani McAlister's edited volume Religion and Politics in the Contemporary United States – adopt the liberal critique. Yet these are two very different books: Christians in the American Empire is a thoughtful polemic that aims to contribute to the public debate, while Religion and Politics in the Contemporary United States offers twenty (including the editors' introduction) scholarly explorations of how religion has operated within American public life.

Rougeau's revision is the more challenging: while he accepts the liberal argument that Christian conservatives have recently dominated the political applications of theology, he is a liberal Catholic who calls for more religion, not less, as the solution. He is worried by trends in American politics, economics, and culture that emphasize rampant individualism at the expense of communitarian social ethics and moral values. America's glaring social and economic inequalities and, especially, its perennially activist foreign policy infuriate him because, he argues, they are unnecessary, un-American, and even unchristian. Relying on traditional Catholic social thought, Rougeau calls for a return to what he says are the true roots of Christianity: concern for the poor, a search for social cohesion and equity, and the promotion of peace. American liberalism, he argues, is poorer for its lack of such a religious core.

Rougeau, of course, is not the first to make this case; he follows in the recently left footsteps of activists Jim Wallis and Michael Lerner, and scholars such as Alan Wolfe, Jeffrey Stout, and James Kloppenberg, in trying to reintroduce American progressivism to its social gospel tradition. Despite an inclination to caricature the political and religious views of conservatives, Rougeau offers a persuasive critique of American political conservatism and its appropriation of conservative Christianity. Still, he is unlikely to have much impact with his fellow liberals, who will undoubtedly cheer his denunciations of conservatism but ignore his idiosyncratic, often eccentric, call for a synthesis of liberalism and Catholicism.

Although they have edited a very different kind of book, Griffith and McAlister also deride conservatives' claims that religion has been absent from the public square. Religion, they and their nineteen individual contributors agree, has never been absent. But they, too, offer a revision on the standard liberal critique: rather than focus solely on the role of Protestant evangelicals and fundamentalists and Catholic neoconservatives, they document the myriad religious influences on American public life, for better or worse. This includes the now-standard evangelicals and fundamentalists, but Religion and Politics in the Contemporary United States will broaden horizons by also focussing on, among others, African American Muslims, women in the (Mormon) Church of Latter-Day Saints, and the spiritual dimensions of Oprah Winfrey's sensationally popular television book club. The religious right, in other words, does not have a monopoly on public faith and its political applications. Indeed, as the diverse nature of the chapters reflects, and as the editors note, religion's role in the public square is sometimes conservative, sometimes liberal, but most often “not clearly classifiable as either” (5). Griffith and McAlister also rightly point out that religion's effects are not always positive or negative, but variable: “As often as it [religion] appears to liberate or empower one group of people, it manipulates, displaces, and exploits another” (ibid.).

It would be impossible to summarize each of the nineteen chapters in the space of such a short review. But the editors are true to their word: few would doubt the diversity of American public religion after reading this excellent book. The chapters are divided into three thematic sections that examine, respectively, how religion engages the state; how religion engages the international, be it through US foreign policy or transnational communities; and how religion and spirituality are expressed through popular culture and the media. In their cogent introduction, Griffith and McAlister offer a superb historiographical overview of trends in both religious studies and American studies – their discussion of religious studies within the academy is especially insightful.

Thus while they offer very different approaches, both Christians in the American Empire and Religion and Politics in the Contemporary United States illustrate that the role of religion in the public square is much more complicated and diverse – and thus more interesting – than critics on the left and right usually allow.