If there is one sober lesson Americans seem to be taking out of the bathos of the Civil War sesquicentennial, it’s the folly of a nation allowing itself to be dragged into the war in the first place. After all, from 1861 to 1865 the nation pledged itself to what amounted to a moral regime change, especially concerning race and slavery—only to realize that it had no practical plan for implementing it. No wonder that two of the most important books emerging from the Sesquicentennial years—by Harvard president Drew Faust, and Yale’s Harry Stout—questioned pretty frankly whether the appalling costs of the Civil War could be justified by its comparatively meager results. No wonder, either, that both of them were written in the shadow of the Iraq War, which was followed by another reconstruction that suffered from the same lack of planning.

What kept the nation feeding an entire generation into the Civil War’s meat grinder, especially if the war’s endgame prospects were so unclear? The answer, in Stout’s version, was American religion. A war which began as a fairly colorless constitutional dispute over secession was transformed by a tidal wave of “millennial nationalism” into a crusade with no off switch. Faust flips the causal equation. If religion did not exactly drive Americans to war, then war drove Americans to religion as the justification for its lethally expensive costs. “The war’s staggering human cost demanded a new sense of national destiny,” wrote Faust, “one designed to ensure that lives had been sacrificed for appropriately lofty ends.” A nation guided by realpolitik knows when to cut its losses. A nation blinded by the moral gleam of a “fiery gospel writ in burnished rows of steel” and charmed by the eloquence of a president with an uncanny knack for making his assessment of political problems sound like the Sermon on the Mount, obeys no such limitations.

There is not much questioning the cultural power of religion in America in the Civil War years. Americans at the midpoint of the 19th century were probably as thoroughly Christianized a people as they have ever been. Landscapes were dominated by church spires, and the most common sound in public spaces was the ringing of church bells. American churches jumped to exponential levels of growth. Between 1780 and 1820, Americans built 10,000 new churches; by 1860, they quadrupled that number. Almost all of the 78 American colleges which were founded by 1840 were church-related, with clergymen serving on the boards and the faculties. Even a man of such modest religious visibility as Abraham Lincoln, who never belonged to a church and never professed more than a deistic concept of God, nevertheless felt compelled, during his run for Congress in 1846, to still the anxieties of a Christian electorate by protesting that “I have never denied the truth of the Scriptures; and I have never spoken with intentional disrespect of religion in general, or of any denomination of Christians in particular … I do not think I could myself, be brought to support a man for office, whom I knew to be an open enemy of, and scoffer at, religion.”

If, in Jefferson’s words, the Constitution had erected a “wall of separation” between the church and the federal government, there was no corresponding wall between church and culture. Closed off from making policy, churches organized independent societies for Bible distribution, for alcoholism reform, for observance of the Sabbath, and for suppressing vice and immorality. And, they grew. By the time the French liberal Alexis de Tocqueville took his celebrated tour of the United States in the 1830s, he was amazed to find that while “in the United States religion” has no “influence on the laws or on the details of political opinions,” nevertheless, “it directs the mores” and through that “it works to regulate the state.”

The question Tocqueville did not ask was whether American religion would always be content simply with cultural dominance, and might not seize an opportunity, if it presented itself, to assert a political role. And if ever there was a moment when it seemed possible that American religion might reassume a managing place in public politics, the Civil War was it. At the height of the war, delegations of concerned clergymen received high-profile audiences with the President; the National Reform Association moved an amendment to the Constitution to add formal recognition of Christianity to its preamble; the military chaplaincy was dramatically expanded as a major component of the U.S. armed forces; and “fully one-third of all soldiers in the field were praying men and members of some branch of the Christian Church,” and religious revivals in the armies converted between 5 and 10 percent of men in uniform.

Above all, it was a time when Christianity allied itself, in the most unambiguous and unconditional fashion, to the actual waging of a war. In 1775, American soldiers sang Yankee Doodle; in 1861, it was Glory, glory, hallelujah! As Stout argues, the Civil War “would require not only a war of troops and armaments … it would have to be augmented by moral and spiritual arguments that could steel millions of men to the bloody business of killing one another...” Stout concentrates on describing how Northerners, in particular, were bloated with this certainty. By “presenting the Union in absolutist moral terms,” Northerners gave themselves permission to wage a war of holy devastation. “Southerners must be made to feel that this was a real war,” explained Colonel James Montgomery, a one-time ally of John Brown, “and that they were to be swept away by the hand of God, like the Jews of old.” Or at least offered no alternative but unconditional surrender. “The Southern States,” declared Henry Ward Beecher shortly after Abraham Lincoln’s election to the presidency, “have organized society around a rotten core,—slavery,” while the “north has organized society about a vital heart, —liberty.” Across that divide, “God is calling to the nations.” And he is telling the American nation in particular that, “compromise is a most pernicious sham.”

But Southern preachers and theologians chimed in with fully as much fervor, in claiming that God was on their side. A writer for the Southern quarterly, DeBow’s Review, insisted that since “the institution of slavery accords with the injunctions and morality of the Bible,” the Confederate nation could therefore expect a divine blessing “in this great struggle.” The aged Episcopal bishop of Virginia, Richard Meade, gave Robert E. Lee his dying blessing: “You are engaged in a holy cause.”

I see it now as I have never seen it before. You are at the head of a mighty army, to which millions look with untold anxiety and hope. You are a Christian soldier—God thus far owns and blesses you in your efforts for the cause of the South. Trust in God, Gen. Lee, with all your heart,” and placing his palsied hands on the General’s head, he added in a voice never to be forgotten by the bystanders, “you will never be overcome—you can never be overcome.”

Holy causes that can never be overcome do not make provision for surrender. Unable to discount the burden of holiness, the South was doomed to resist beyond any point of reason, until its back had been broken on the war’s wheel.

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These descriptions of the moral intoxication into which Americans drank themselves in 1861 fit the Civil War seamlessly into a larger pattern of American war making, since Americans love to imagine that when they fight, they fight for right, rather than for treacly political advantage. But so does everyone else, at least since the heyday of absolute monarchies. And I suspect that the prolonged blood-letting of the Civil War had much less to do with a collision of two causes, convinced in typical American fashion of their own purity, and more with pitilessly exposing the fissures in the absolutes of both sides. Eventually, the Civil War would render moral absolutism less, rather than more, believable, and with long and unhappy consequences for American religion.

The preachers of 1861 might see church and state marching as to war, but it certainly did not look that way on the ground. That paragon of martial piety, the Confederate General “Stonewall” Jackson, had a very poor estimate of the influence of Southern religion in time of war. “I am afraid that our people are looking to the wrong source for help, and ascribing our successes to those whom they are not due,” Jackson complained, “If we fail to trust in God & to give him all the glory our cause is ruined. Give to our friends at home due warning on this subject.”

So little provision had been made for chaplains’ services in the Army of Northern Virginia that fully half of the regiments in Jackson’s corps in the spring of 1863 were without one. In the Union Army, religion seemed to have just as meager a grip, despite the numbers of “praying men.” “It is hard, very hard for one to retain his religious sentiments and feelings in this Soldier life,” admitted one New Jersey surgeon. “Every thing seems to tend in a different direction. There seems to be no thought of God of their souls, etc. among the soldiers.”

One Iowa soldier found himself enlisted in a company of German free thinkers, and was aghast to discover “they are the worst men I ever saw … They never think of God or that they have a Soul.” Or if soldiers did have thoughts about God, they were liable to be blasphemous ones. An Ohio cavalryman, disgusted by an “old cust of a Preacher” who claimed “God has fought our battles and won victorys,” concluded that the preacher must surely have “lied like Dixie.” If God had really done all that, “why is it not in the papers and why has he not been promoted.”

For every Northern divine claiming God’s favor for the Union, and every Southern one claiming God’s favor for the Confederacy, there were far more who could not make up their minds what to say about slavery. And taken together, they created a popular perception that religion had nothing reliable or coherent to say about the greatest American issue of the 19th century.

Charles Hodge, the greatest of America’s 19th-century theologians, had been shifting ground on slavery for 20 years. In the 1840s, Hodge deplored any suggestion that “slave-holding is itself a crime” as “an error fraught with evil consequences.” Ten years later, Hodge veered around to saying that slavery in the abstract might not be evil, but to practice slavery “in almost all” cases leads the slaveholder to practice evil. On that logic, Hodge concluded, “Emancipation is not only a duty, but it is unavoidable.” By 1864, Hodge was endorsing a Presbyterian General Assembly resolution that unequivocally branded slavery as “an evil and guilt.” With so much tacking before the political winds, how were the churches to give any worthwhile bearings to the people?

Abraham Lincoln was another thinker who tacked before the winds. Lincoln was certain that “God wills this contest, and wills that it shall not end yet.” But that was because Lincoln had been raised in a Calvinist household where every event, war or peace, was considered a predestined product of God’s will. What was more difficult for Lincoln to determine was what, exactly, God had willed this war for. In 1861, when his friend, Orville Hickman Browning, asserted, “Mr. Lincoln we can’t hope for the blessing of God on the efforts of our armies, until we strike a decisive blow at the institution of slavery,” Lincoln replied, “Browning, suppose God is against us in our view on the subject of slavery in this country, and our method of dealing with it.”

This problem bothered Lincoln enough that he took it as the central theme of his second inaugural address. “Neither party expected for the war, the magnitude, or the duration, which it has already attained,” Lincoln observed. What is more, “Both read the same Bible, and pray to the same God; and each invokes His aid against the other.” Lincoln could not very easily declare his own side wrong about the Bible and God, but he could not, in similar fashion, nerve himself morally to throw all the opprobrium into the other balance. “It may seem strange that any men should dare to ask a just God’s assistance in wringing their bread from the sweat of other men’s faces,” he said, but he would allow himself no more than to find the Confederate argument “strange.” In the end, Lincoln opted for Calvinist agnosticism, which cloaked the will of God in mysterious ways, and left humanity with only the gentle reminder that “The Almighty has His own purposes.” There would be no ethical victory lap for Lincoln, no deus vult for a righteous and victorious Christian Union; instead, Lincoln enjoined the nation to behave “with malice toward none; with charity for all.

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Instead of American religion corrupting the Civil War with absolutism, it is more possible to say that the Civil War corrupted American religion. An Iowa sergeant, shocked at the carnage at Shiloh, wondered, “Oh my God! Can there be anything in the future that compensates for this slaughter?” Religious discourse would become plagued more and more by incessant questioning, by decaying faith, and an increasing appeal to feeling and imagination over against confessional reason or evangelical conversion, and that did not provide much weaponry for an adventure into public forums.

“Perhaps people always think so in their own day, but it seems to me there never was a time when all things have shaken loose from their foundations,” wrote one of the correspondents of the popular revivalist, Charles Grandison Finney, in 1864, “So many are sceptical, doubtful, so many good people are cutting loose from creeds & forms ... I am sometimes tempted to ask whether prayer can make any difference.” Far from feeling satisfied that the North had pursued a righteous crusade to its fulfillment, Finney himself was enraged that, after two years of war, “in nopublick proclamation either north or south is our great national sin recognized.”

William James, who ducked service in the war but who watched it wreck the lives of two of his brothers, concluded that the idealism which had led them to volunteer had been a destroying angel, and that it would be far better to regard ideas as instruments which help people adapt to their circumstances, rather than abstract truths which they allow to govern their actions. In his post-war career at Harvard, James formulated an entirely different way of understanding ideas, which he called pragmatism.

Beliefs had to be judged by their consequences, James insisted, by whether they had “cash value in experiential terms” and could be converted into useful practical conduct. Giving abstractions like abolition and freedom some absolute status as truth made them into the lethal and uncompromising tyrants which decimated James’s generation. But without the status of truth, religion degenerated into therapy—which, from James’s perspective, was not necessarily a bad thing.

For Southerners, the war laid an even heavier burden on religion. Edward Porter Alexander, who ended the war as a brigadier general in Robert E. Lee’s army, thought that religion had paralyzed Southerners more than energized them. “I think it was a serious incubus upon us that during the whole war our president & many of our generals really & actually believed that there was this mysterious Providence always hovering over the field & ready to interfere on one side or the other, & that prayers & piety might win its favor from day to day.”

When, by 1864, defeat was looking the Confederacy in the eyes, the arms of the pious dropped nervelessly to their sides, and they concluded that God was deserting them, if not over slavery, then for Southern unbelief. “Can we believe in the justice of Providence,” lamented Josiah Gorgas, the Confederacy’s chief of ordnance, “or must we conclude we are after all wrong?” Or even worse, wailed one despairing Louisianan, “I fear the subjugation of the South will make an infidel of me. I cannot see how a just God can allow people who have battled so heroically for their rights to be overthrown.”

However confident the Beechers and Bushnells had been at the beginning of the war that they could read God’s “righteous sentence by the dim and flaring lamps,” the war itself proved otherwise. If anything, American religion became one of the Civil War’s major cultural casualties. And contrary to Stout, the Civil War was not prolonged or made more intractable by religion, or at least not by religion alone.

Total war, as Yale law professor James Whitman has recently written, was the result of politics, and particularly by the movement of governments in the 19th century away from monarchy and toward popular democracy. So long as government had been the private preserve of kings, then wars had been the sport of monarchs, and were fought as though they were princely trials by combat or a species of civil litigation. The only class of people likely to suffer severely by them was the nobility. The scope of war was limited simply because war was understood to be the prerogative of kings.

But once democratic governments began to shoulder the monarchs aside—once governments became “of the people, by the people, for the people” and involved the entire people of a nation and not just a handful of aristocrats—war became the instrument of entire populations. No solitary monarch could now call them off; no gentlemen’s agreement could limit their scope. Wars became wars of nations against nations, waged for principles abstract enough to command everyone’s assent, and therefore all the more impossible to win short of the annihilation—not just the defeat—of an enemy. Not religion, but democracy made it necessary to invoke “millennial nationalism,” in order to recruit sufficient mass resources for new mass wars. Theories about justice in war or debates about the proportionality with which war could be waged would only serve as obstacles in the path to unconditional victory.

From the Civil War onward, American Protestantism would be locked deeper and deeper into a state of cultural imprisonment, and in many cases, retreating to a world of private experience in which Christianity remained of little more significance to public life than stamp-collecting or bridge parties. Appeals to divine authority at the beginning of the Civil War fragmented in deadlock and contradiction, and ever since then, it has been difficult for deeply rooted religious conviction to assert a genuinely shaping influence over American public life.

In exposing the shortcomings of religious absolutism, the Civil War made it impossible for religious absolutism to address problems in American life—especially economic and racial ones—where religious absolutism would in fact have done a very large measure of good. Some leaders, Martin Luther King prominent among them, have since invoked Biblical sanction for a political movement, but that has mostly been tolerated by the larger, sympathetic environment of secular liberalism as a harmless eccentricity which can go in one ear and out the other. “Never afterward,” wrote Alfred Kazin of the war, “would Americans North and South feel that they had been living Scripture.” I do not know that Americans have been the better for it.