Sword of the Spirit, Shield of Faith was written under the assumption that religion played an important role in shaping American perceptions of the world and in contributing to domestic debates on how the United States should engage with other nations. It is an exploration not of whether religion influenced U.S. foreign relations, but how. It is a logical assumption: few would argue that religion has not played a consistently important role in American life, for better or worse.
This last qualifier — for better or worse — is important, for this book also operates under the assumption that religion is just like any other historical topic. It is not my desire, and certainly not my intention, to make a case either for or against a role for religion in public life. Readers will of course use the material in this book to support their own beliefs that religion is either a productive or a pernicious force in American foreign relations. Partisans on both sides of the acrimonious debate over religion's place in the public square — and increasingly over the nature of religion itself — will find plenty of evidence to back up their competing claims. But such quarrels are not my concern. Religion provokes intense emotions, and no historian is free of bias. Nonetheless, I have sought to treat my subject as objectively as possible.
Doing so has meant recognizing that there was not one religious influence upon American foreign relations, but many: nationalist but also internationalist, exceptionalist but also cosmopolitan, nativist but also tolerant, militant but also pacifist. The religious influence was neither monolithic nor consensual but a product of intense dialogue, debate, and controversy. Nor did it always push U.S. foreign policy in the same direction. It is a fascinatingly complex story, but its very complexity makes its unraveling all the more important and worthwhile.
But why focus on religion at all? Why does it matter to American diplomatic history? Aside from the personal faith of individual policymakers, religion has been integral to American politics and culture, and to America's sense of itself, and thus also to the products of politics and culture, such as foreign policy. More specifically, religion has had an almost uniquely intimate relationship with American war and diplomacy. In times of war, religious liberals and conservatives, militants and pacifists, have all called upon God to sanctify their cause, and all have viewed America as God's chosen land. As a result, U.S. foreign policy has often acquired the tenor of a moral crusade.
Moreover, the religious mindset was geographically limitless; those who possessed it were concerned not only with their community, state, or country, but the entire world. As immigrants, generations of American Christians, Jews, and Muslims thought of themselves as members of a transnational faith that transcended national boundaries. They kept in regular contact with coreligionists overseas and followed the political affairs in foreign countries that affected these spiritual kinfolk. They sought to spread the gospel to people who had never heard of Christ and endured incredible hardship in doing so. They were more likely to live and travel abroad and more likely to have a foreign correspondent. Unlike most of their fellow citizens, then, religious Americans inherently thought of themselves as citizens of the world. They paid closer attention to foreign affairs and were more likely to allow international developments to affect their political views. Thus while religious faith helped create an American nationalism, it also fostered a powerful sense of internationalism.
Since the late sixteenth century, long before the United States existed, religion has played an important role in shaping Americans' perceptions of the wider world. In both popular debates about American engagement with the world and the foreign policies that have emerged from these debates, religion has been a major factor. The religious influence — indeed, religious faith itself — has not always been strong or consistent. But though it has ebbed and flowed, it has always been there.
This seems to be a basic point — religion matters, and always has — yet it is an important one to make because it has been so neglected in explaining the history of American war and diplomacy. Historians have emphasized a wide array of factors, from traditional concerns such as economics, national security, and military strategy, to newer theories based on race, gender, culture, and postmodernism. All are important grounds for inquiry, and all have yielded a rich understanding of the American past. Yet until very recently, religion was seen as a mystifying sideshow, an irrational impulse born of a "paranoid style" that clouded the realist assumptions of high diplomacy. Even after diplomatic history's cultural turn — an exciting development over the past two decades that has pushed scholars to incorporate race, class, and gender into the American diplomatic tradition — and its international turn, which portrays the United States as "a nation among nations," religion remains peripheral or nonexistent. This is true for otherwise superb overviews of U.S. foreign policy that purport to examine American "ideals," "style," "ideology," "mission," "Wilsonian idealism," "core values," even "why America fights" — normative topics, in other words, that are ideally suited to religious ideas and values and incomplete without them. In fact, until very recently religion was sidelined in most fields of modern American history. Be it the history of politics, immigration, or civil rights, religious faith was pushed to the margins when it made any appearance at all. It seemed that only historians of American religion took religion seriously, an absurd situation when one considers the prevalence and importance of religion in American life.