The core historiographical critique and call to action from Jon Butler’s “Jack-in-the-Box Faith: The Religion Problem in Modern American History” has permeated the field of U.S. foreign relations history, yet it has done so indirectly. Even though scholars have observed an extensive and durable “religious turn” in the field over the past two decades, there are relatively few books or articles in U.S. in the world or U.S. foreign relations history that cite Butler’s essay or identify it as the inspiration for embedding religion in their studies.Footnote ¹ This is perhaps not surprising, as Butler’s discussion of “the religion problem in modern American history” focused exclusively on the domestic.Footnote ² The term “international relations” appears just once in the article, and then only to position the field of foreign relations as one among many that competed with religion “for static page space in American history textbooks.”Footnote ³ The Second World War and the Vietnam War appear only in reference to their influence on domestic culture, politics, or social movements. Butler was cogent and correct in arguing that we cannot understand modern American history without understanding religion—but American politics, culture, technology, business, and religion did not stop at the water’s edge in the twentieth century. Thankfully, many foreign relations scholars have recognized that we cannot understand the role of the United States in the world without grappling with religion at a fundamental level.

Calls to incorporate religion more integrally into the study of U.S. diplomatic history predate Butler’s article, but if we might identify any foreign relations scholar as a prophet for the “Jack-in-the-Box Faith” critique, it would have to be Andrew Preston.Footnote ⁴ In 2006, Preston published a call-to-arms/state-of-the-field essay in Diplomatic History titled “Bridging the Gap Between the Sacred and the Secular in the History of American Foreign Relations,” which urged diplomatic historians “to pay more attention to religion.”Footnote ⁵ This is not to say that prior to 2006, diplomatic historians had not incorporated religion into their scholarship; much of “Bridging the Gap” is a review of the then-extant foreign relations literature that incorporated religion. Preston highlighted the work of Ernest Lee Tuveson, Anders Stephenson, Kevin Phillips, Andrew Rotter, Seth Jacobs, and Melani McAlister as noteworthy examples of scholarship that took religion seriously.Footnote ⁶ However, he argued that in general, foreign relations scholars had tended to “briefly, idiosyncratically, and opportunistically highlight the role of certain individuals or incidents,” but had not “deployed religion as an overall theory or method to examine America’s role in the world.”Footnote ⁷ In other words, their incorporation of religion epitomized the “jack-in-the-box effect” that Butler had identified.Footnote ⁸ He also shared some of Butler’s diagnoses for why this was the case, including (mistaken) assumptions about U.S. secularization in addition to the methodological challenges that religion presents and concerns about the appearance of “partisanship and advocacy” for a particular faith tradition.Footnote ⁹

To overcome these obstacles, Preston offered a framework for integrating religion into the study of U.S. foreign relations in a systematic, holistic manner. In light of the need for historians to demonstrate a causal relationship “between religious matters and diplomatic events,” he recommended scholars “look to the historians of gender and race as exemplars” for illuminating causality from complex social and cultural forces.Footnote ¹⁰ Accordingly, he suggested that biographical methods might offer direct insight into the religious motivations of policymakers or activists, and that social or cultural historical methods might uncover indirect influence, such as “the values, norms, and ideas” undergirding policy formation.Footnote ¹¹ Six years after “Bridging the Gap,” Preston published his magisterial Sword of the Spirit, Shield of Faith: Religion in American War and Diplomacy, which put that framework into practice through a full survey of religion and U.S. foreign relations since the seventeenth century.

A significant number of books and articles have joined Sword of the Spirit in the nearly two decades since the publication of “Bridging the Gap,” and the Society for Historians of American Foreign Relations (SHAFR) annual meeting now regularly features multiple panels and papers that center religion.Footnote ¹² Furthermore, as Daniel Hummel has noted, scholars and “historians from other fields have even more dramatically expanded the boundaries of America and the World,” bringing their disciplinary perspectives to bear on subjects “from transnational religious networks to the religious beliefs of policy makers to American religious thought” and beyond.Footnote ¹³

The confluence of U.S. foreign relations scholars engaging with religion and scholars from religious studies and other fields engaging with U.S. in the world history has brought religion into the historical mainstream of the subfield. On topics that Andrew Preston suggested had already had their religious aspects examined thoroughly in “traditional” diplomatic history accounts—like particularly devout policy leaders, overseas missionaries and imperial expansion, or the religious roots of key ideologies—scholars such as Cara Lea Burnidge, William Inboden, Emily Conroy-Krutz, Gale Kenney, Diane Kirby, and Kate Moran, who foreground religion in their work and who are trained to analyze religion from a critical historical perspective, have added unparalleled depth and complexity.Footnote ¹⁴ For example, in both Christian Imperialism and Missionary Diplomacy, Emily Conroy-Krutz’s sensitive analyses of U.S. Protestant missionaries in the early American Republic and the late nineteenth and early twentieth century respectively reveal the dynamism and diversity of imperialism, the foundations of exceptionalist ideologies, and the actions, interactions, and mental geographies and hierarchies that shaped how Americans made sense of the world at significant moments for U.S. foreign relations.Footnote ¹⁵ Her work underscores just how fundamental overseas missionary work was to the formation of U.S. national identity, international engagement, and power in the nineteenth century, and the sophisticated insights and knowledge about religion that she offers are integral both to her analyses and to her contributions to the literature. Biographical treatments of key leaders that take religion seriously have been similarly illuminating. The rich analyses that Malcolm Magee, Mark Benbow, and Cara Burnidge develop in their books on Woodrow Wilson, for instance, make manifest the inseparability of Wilson’s religious beliefs (theological as well as cultural) and his liberal internationalist vision for the world order, approach to diplomacy, and mode of decision making.Footnote ¹⁶

Scholars have also expanded their explorations of religion beyond the realms covered in earlier diplomatic histories, delving into every aspect of the U.S. engagement with the world, from the transnational religious connections that shaped the American Revolution and religious life in the United States after independence to advocacy for religious freedom as a tool for bolstering or resisting U.S. foreign policy aims globally.Footnote ¹⁷ Katherine Carté’s Religion and the American Revolution delves deeply into the transatlantic networks that linked British and colonial American protestants, undergirded by state policies—including establishment—that functioned as an “imperial scaffolding” and privileged certain denominations.Footnote ¹⁸ When the American Revolution rent that scaffolding, it fundamentally reshaped religious life and the relationship between church and state in the new United States. Carté’s incisive exploration underscores the changes that revolution and war brought to religion itself in the United States, not to mention to broader principles of religious liberty that fostered religious pluralism in the new nation. In later centuries, U.S. religious groups mobilized to try to influence foreign policy, drawing on information gained through networks with their co-religionists abroad and empowered politically by notions about religious liberty as a foundational national value. This is a phenomenon that I examine in my work on evangelical foreign policy engagement during the late Cold War, and that scholars such as Ashlyn Hand and Theresa Keeley have also explored extensively.Footnote ¹⁹

Whether they are covering war or peace, state or nonstate actors, grassroots activists or non-government organizations, bilateral or multilateral policymaking, intellectual currents or mass media, historians are engaging the reciprocal questions of how religion shaped U.S. foreign policy and how foreign affairs shaped U.S. religion.Footnote ²⁰ The recent edited volume Global Faith, Worldly Power: Evangelical Internationalism and U.S. Empire includes insightful chapters from Cristina Davidson, Tom Smith, Helen Jin Kim, David Kirkpatrick, and many others that make clear that U.S. evangelical engagement abroad was never simply a one-way missionary endeavor and that international encounters changed U.S. evangelicalism in fundamental ways.Footnote ²¹ Crucially, even diplomatic historians who have not made religion the central focus or mode of analysis for their work have sought to identify and address it more holistically as a factor in their studies; in the most recent SHAFR presidential address, for example, Mitch Lerner devoted considerable space to outlining the multidimensional influence of religion in U.S.-Korean relations.Footnote ²² Future scholarship will hopefully build on recent and forthcoming work that illuminates the religious factors in histories of contemporary foreign policymaking, immigration, race, and national identity formation, and of relations with less well-studied regions while also employing methods from material culture studies, intellectual history, religious studies, and other fields.Footnote ²³

That said, focused methodological training will be necessary if we are to hope that all diplomatic historians might someday account for religion in a thoughtful, intentional, and comprehensive manner. As Sandra Scanlon has argued, “these scholarly endeavors will be most successful when the fields of religious studies and U.S. foreign relations are interwoven, a demand that requires extensive knowledge and training in both areas.”Footnote ²⁴ Graduate students in the field need careful guidance and contextual knowledge to “see” religion in their primary sources and to make meaning from what they are seeing. Fortunately, one of the main methodological texts for diplomatic historians—Explaining the History of American Foreign Relations—includes a chapter by Andrew Preston with practical guidelines for using religion as a category of analysis.Footnote ²⁵ There is room to further develop and systematize the framework he offers, and to incorporate additional critical tools from other disciplines, but the inclusion of this chapter in this foundational text does signal to students that they should be thinking seriously about religion. With any luck, we will continue to see exciting new work on religion in U.S. in the world history that avoids the jack-in-the-box approach of earlier generations.