After completing a book exploring moral and religious dimensions in America's Civil War, I briefly considered expanding the scope of my subject broadly to write a book on the subject of “Religion, War, and the Meaning of America.” In preparation for that work I wrote a brief essay and then shelved the project for a year to explore another subject. In retrospect, the shelving was the smartest thing I ever did, for in the interim between that essay and now, I have read the book I intended to write. Andrew Preston's Sword of the Spirit Shield of Faith is easily the finest book on religion, diplomacy, war and American History ever written. Both in scope of coverage and depth of analysis it manages to cover the entire history of war and America from colonial origins (wars with the Indians, the French, and the English) through Vietnam, with a closing nod to the Middle East and the presidency of Barack Obama.

Preston frames his argument with the stark recognition that for all the significance of war in American History and American diplomacy, and for all of the discoveries of the “religious factor” in American life, no one previous had seriously examined the intersections of these two overwhelming forces across the broad spectrum of American history. Part of the reason for this is the way professional scholarship is divided up. Diplomatic historians do not, for the most part, take religion seriously (hence the State Department's utter shock at encountering the power of radical Islam), nor do religious historians weave war into their narrative. If one examines the five or six most influential histories of religion in American history, as I have done, one will find hardly anyone devoting more than a page to any American war. Indeed peace movements receive greater coverage, even though their influence in shaping American public life pales beside America's ongoing history of perennial war. Preston aims to close that gap and does so brilliantly. Having already established his credentials as a diplomatic historian, Preston engages the literature on religion in American history with a thoroughness that explores virtually every significant source on religion running all the way back to the Puritans.

Preston recognizes the stark differences between diplomacy and religion and correctly observes that both would like to completely ignore the other. U.S. foreign policy has never been driven by ideals at the expense of naked self-interest, but always existed within a frame of meaning that aggressively pursued American self-interest in the world. Religion, on the other hand has always been idealistic, because it is faith-based—(even Reinhold Niebuhr's famous realism was grounded in the hope of spiritual transformation and redemption). This dialectic, in turn, compelled American statesmen—especially presidents—to mouth idealistic sentiments for whatever turns to war they might wish to make (think Woodrow Wilson's war to end all war), because they had to satisfy a populace raised as much on biblical ethics as national war-making. Complicating matters still further, many, indeed most presidents and major statesmen, were themselves religious figures to one degree or another, and found ways to drape their realpolitik in religious garb.

The consequences of this alliance between diplomacy and religion are, as Preston convincingly argues, decidedly mixed. At times American leaders encountered enemies who were genuinely evil and required the restraining intervention of American war-making might. At other times, American leaders imbibed what Senator William Fulbright famously labeled “the arrogance of power” and confused might with right, plunging America into immoral campaigns and unjust wars. If forced to come down on one side or the other, I would conclude from Preston's accounts of multiple engagements that more often than not, American statesmen erred on the side of arrogance.

In a break from the anti-Puritan synthesis that characterizes much of contemporary American historiography, Preston documents how thoroughly Americans have imbibed the rhetoric and reality of Puritan thought. Puritan thought virtually defined the enduring American identity as a “New Israel” and “redeemer nation.” By identifying themselves as God's special agent to effect good in a fallen world, Puritan intellectuals established a mindset of American “exceptionalism” that has never gone away. Central to this identity is the notion that American behavior cannot be judged by the same ethical standards applied to other purportedly profane nations. Just as Israel could launch offensive wars in Canaan as God's chosen people, so America, imbued with a similar redemptive mission could launch preemptive wars of choice knowing that God was on their side.

Puritan actions reinforced thought and, again, shaped an enduring legacy. When faced with resistance from Indians, and later French, and still later English competing powers, Puritans established a two-fold response that continues to govern American religious and military rhetoric. The first response is that war comes as God's corrective judgment to a backslidden people. In this framework, God imposes war on His people to encourage repentance and reformation. The second response pivots from the sinner to those who wage war on God's chosen people. These are sinners beyond national redemption. Profane war-mongering peoples may indirectly serve God's purposes of inciting reformation, but directly they incur the wrath of God for killing His people. With reformation in hand, victory over “satanic” enemies was virtually assured.

Americans were decidedly not the first nation to endorse such messianic rhetoric. England, for one, thought of itself as an “Elect Nation” in the seventeenth-century and beyond. And at this level one could question Preston's enterprise with a “so what?” Aren't American statesmen and theologians doing exactly what other great powers did during their day in the sun? Preston does not directly address this caveat—why bother to address the obvious—but his answer is implied throughout the long history of war and religion in American history. Specifically, the rhetoric of exceptionalism continues to drive and legitimize foreign policy in America, where it does not in England, for the simple reason that America has yet to lose the big wars, or find itself displaced as the number one superpower. The rhetoric of exceptionalism lives on as a reflection of brute fact as long as American might goes unmet. Would God ever bless a godless nation to the point of global dominion? Only if it is Armageddon, at which point the future would either be an American-led millennium, or universal doomsday.

How long America will remain the world's major superpower with a religious ethic grounded in the “Judeo-Christian” tradition is an open question. But as long as it does, one can reasonably conclude from Preston's exhaustive narrative, that the rhetoric of exceptionalism will continue to animate and accompany unending wars.