After the short Spanish–American War ended in 1898, the United States was left in control of what remained of the former Spanish Empire and was faced with the problem of what exactly they were to do with this collection of islands scattered across the Caribbean and Pacific. Susan Harris's new book tracks the development of American identity during this period in US history, a period which the author feels is still largely unrecognized in the collective US consciousness – even if numerous scholars, such as Paul Kramer and Julian Go, have brought this era to academic attention in recent years.

On the face of it, Harris's book focusses on two issues that have been investigated usefully by others: the roles of race and religion during the period of US overseas imperialism. However, Harris illustrates that the role of religion has still been underexplored, and her work goes on to fulfil her aim of showing how the “idea of the United States as a Christian nation is intricately tied into Americans’ understanding of their national history, identity, and mission” (30). Indeed, as the book's title suggests, Harris's monograph takes US Christianity as its primary theme, illustrating how leading public figures of the era used the rhetoric of Christian mission to both criticize and justify expansionism and imperialism, particularly in the Philippines.

Harris's exploration of primary literature is the backbone of her work and her analysis of US schoolbooks, for consumption both at home and in the Philippines, provides some of the most original and insightful parts of her work. However, by tackling literary giants like Mark Twain and Rudyard Kipling, the author has to negotiate better-trodden ground. Harris's discussion of Twain and his writings displays the understanding one would expect of somebody who has already published two books on the author. For historians of this period, Harris's expertise offers a valuable addition to the understanding of the role played by writers such as Twain from somebody who comes from a more clearly literary background.

In addition to her analysis of a wide range of contemporary writings and speeches from the United States, Harris provides a useful international perspective on US imperialism in the final section of her book, entitled “The Eyes of the World.” In addition to Britons like Kipling, Harris brings to light a host of quite different voices from across Europe, Latin America and the Philippines. For example, Harris discusses the writings of Nicaraguan poet Rubén Darío, who noted how far the US was departing from its supposed Christian mission in taking the path of overseas expansion. It is this diversity of perspectives that offers something distinct from the majority of existing literature examining this period.

Overall, Harris has gathered together an extensive range of primary documents and other sources to provide a thoughtful analysis of the role of religion and religious rhetoric in the American imperial experiment at the beginning of the twentieth century. As Harris's epilogue overtly suggests, “religion remains a key value in American identity politics” today and her work helps readers to reflect on how little might have changed in terms of an American sense of “mission” over the last century or so (197).