In October 1863, Lincoln prepared two versions of remarks to the Baltimore Presbyterian Synod. In the first, though not the second, he remarked: “I have often wished that I was a more devout man than I am.” His meaning is obscure. It could have been a statement of humility, refusing to claim for himself the mantle of faith, or it could just as likely have meant Lincoln was not devout. But two points are salient. One is that Lincoln’s writings from his earliest days to his final speeches are shot through with Biblical references—from the “house divided” to, replying to a speech by the mayor of Philadelphia when he was en route to his inauguration, saying “may my right hand forget its cunning and my tongue cleave to the roof of my mouth, if I ever prove false to [the teachings of the Declaration]”—and his meditations on divinity grew as the crisis of the Civil War mounted. The second is that he “wished” he was “more” devout, which is to say he felt some devotion and, significantly, wished to feel more. The presence of this devotion was evident the next month in the Gettysburg Address, in which Lincoln appeared extemporaneously to have added the qualification “under God” to the phrase “this nation.”

Several commentators, including David Lowenthal and Richard Brookhiser, have concluded that Lincoln may have been an atheist. Some of Lincoln’s contemporaries suspected the same. In his 1846 campaign for Congress, he was compelled to deny being a “scoffer at religion.” He suggested he had repudiated his early belief in the Doctrine of Necessity, the belief that undermined free will by holding, as Lincoln put it, “that the human mind is impelled to action, or held in rest by some power, over which the mind itself has no control….” Lincoln said he could not support an “open enemy” of religion, if only because such cynicism would “insult the feelings, and injure the morals, of the community in which he may live.”

But Lincoln was remarkably reflective about divinity—never in sectarian or orthodox terms, to be sure, but not in areligious ones either— especially but not exclusively during the war. He employed references to God and the Creation in the context of slavery repeatedly, as in the 1858 speech at Lewistown: The Declaration reflected the founders’ “enlightened belief, nothing stamped with the Divine image and likeness was sent into the world to be trodden on, and degraded, and imbruted by its fellows.” As president, Lincoln received a petition from the historian and diplomat George Bancroft in November 1861 asserting that “Civil war is the instrument of Divine Providence to root out social slavery….” Lincoln responded sympathetically but prudently: That “main thought …is one which does not escape my attention, and with which I must deal in all caution, and with the best judgment I can bring to it.” The next year, he responded to a delegation of Evangelical Lutherans in tones that linked Divinity with progress: “[I]f it shall please the Divine Being who determines the destinies of nations that this shall remain a united people, they will, humbly seeking the Divine guidance, make their prolonged national existence a source of new benefits to themselves and their successors, and to all classes and conditions of mankind.”

Lincoln issued several proclamations of national fast days that were striking for their suggestion that sin and faithlessness caused the bloodshed. In 1861, for instance, he complied with a congressional request that he proclaim a national fast day. The proclamation was frank in its acknowledgment of human frailty and divine superintendence of the war:

And whereas it is fit and becoming in all people, at all times, to acknowledge and revere the Supreme Government of God; to bow in humble submission to his chastisements; to confess and deplore their sins and transgressions in the full conviction that the fear of the Lord is the beginning of wisdom; and to pray, with all fervency and contrition, for the pardon of their past offences, and for a blessing upon their present and prospective action….

A March 1863 proclamation, issued at the behest of a Senate with which he “fully concurred,” went even further. The nation had prospered since its founding. “But we have forgotten God…. Intoxicated with unbroken success, we have become too self-sufficient to feel the necessity of redeeming and preserving grace, too proud to pray to the God that made us! It behooves us then, to humble ourselves before the offended Power, to confess our national sins, and to pray for clemency and forgiveness.”

After major Union victories, it was often Lincoln’s custom to proclaim days of thanksgiving, as he did just after Gettysburg in July 1863 in his characteristically encouraging rather than anathematic tones: “I invite the People of the United States to assemble on that occasion in their customary places of worship, and in the forms approved by their own consciences, render the homage due to the Divine Majesty, for the wonderful things he has done in the Nation’s behalf….” Following the capture of Atlanta, he called for “devout acknowledgement to the Supreme Being in whose hands are the destinies of nations.”

There is a sense of remove in some of these references to “the Supreme Being” or the “Divine Majesty.” But while Lincoln was never an orthodox Christian, he plainly felt a deep and, crucially, personal faith that deepened with crisis. In his farewell address to the people of Springfield in February 1861, as he departed for his inauguration as president, he noted the gravity of the secession crisis. “Without the assistance of that Divine Being, who ever attended him, I cannot succeed. With that assistance I cannot fail.” Along the journey to Washington, he told the New Jersey Senate that “I shall be most happy indeed if I shall be an humble instrument in the hands of the Almighty, and of this, his almost chosen people, for perpetuating the object of that great struggle,” by which he meant the American Revolution’s devotion to natural equality.

This notion of being a “humble instrument” fermented in Lincoln through the war. He wrote to Albert Hodges in April 1864 that his belief in the policies of his administration was “no compliment to my own sagacity”: “I claim not to have controlled events, but confess plainly that events have controlled me. Now, at the end of three years struggle the nation’s condition is not what either party, or any man devised, or expected. God alone can claim it. Whither it is tending seems plain. If God now wills the removal of a great wrong, and wills also that we of the North as well as you of the South, shall pay fairly for our complicity in that wrong, impartial history will find therein new cause to attest and revere the justice and goodness of God.” Observe the grounding in circumstance implicit in the notion of being controlled by events. This separates Lincoln’s greatness from our contemporary quest for presidential legacies, which fuels change for change’s sake.

Similarly, in an 1862 “Meditation on the Divine Will,” Lincoln wrote that God’s purpose in the Civil War might not be that of either North or South: “I am almost ready to say this is probably true—that God wills this contest, and wills that it shall not end yet. By his mere quiet power, on the minds of the now contestants, He could have either saved or destroyed the Union without a human contest. Yet the contest began. And having begun He could give the final victory to either side any day. Yet the contest proceeds.” These Divine purposes were not always comprehensible. He wrote in September 1864 to Eliza Gurney, the head of a visiting delegation of Quakers, that Americans had hoped the “[t]he purposes of the Almighty are perfect, and must prevail, though we erring mortals may fail to accurately perceive them in advance.”

“Erring mortals” is an important formulation. History easily enough demonstrates that feeling like an instrument of God can make leaders into zealots. But Lincoln’s theology was eminently prudent. First, he used it as often to chasten as to inspire, as we have seen in the fast-day proclamations. Second, Lincoln felt religion was reconcilable with reason, which provided it with prudential grounding. Campaigning for the Whig ticket in Worcester, Massachusetts, in 1848, Lincoln was the essence of classical prudence: He denied both the Free Soil claim that Whigs were pro-slavery and the abolitionist argument that men should “do their duty and leave the consequences to God.” The latter “merely gave an excuse for taking a course that they were not able to maintain by a fair and full argument. To make this declaration did not show what their duty was. If it did we should have no use for judgment, we might as well be made without intellect….”

Speaking at Cincinnati in September 1859, Lincoln declared: “I hold that if there is any one thing that can be proved to be the will of God by external nature around us, without reference to revelation, it is the proposition that whatever any one man earns with his hands and by the sweat of his brow, he shall enjoy in peace.” In Hartford in 1860, Lincoln repeated this Thomist analysis of slavery: “I think that if anything can be proved by natural theology, it is that slavery is morally wrong. God gave man a mouth to receive bread, hands to feed it, and his hand as a right to carry bread to his mouth without controversy.” The key word in both instances is “proved.” Faith was accessible to reason, and the particular conclusion that slavery was wrong did not require revelation. But prudence was necessary in the application of reason in such matters. In a private note written around 1858, Lincoln observed that “[t]he sum of pro-slavery theology seems to be this: ‘Slavery is not universally right, nor yet universally wrong; it is better for some people to be slaves; and, in such cases, it is the Will of God that they be such.’ Certainly there is no contending against the Will of God; but still there is some difficulty in ascertaining, and applying it, to particular cases.” This is precisely the kind of prudence that Aquinas said imparted human freedom: a Divine end with prudential choice of means for attaining it.

Lincoln’s prudent theology reached its apotheosis in his Second Inaugural. There, Lincoln acknowledged a unity of North and South under the same God, to Whom both sides prayed, even as he delivered the damning indictment: “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; but”—immediately soothing the severity of Genesis with the mildness of Matthew—“let us judge not that we be not judged.” Twice the Biblical imagery subtly shifts. In Genesis, as Smith has noted, to eat by the sweat of one’s own brow is a punishment; here it is a privilege. The emphasis is on “other”: the sin is to wring one’s bread from the sweat of other men’s faces. In Matthew, as Smith has also emphasized, the passage “judge not” is an admonition: Judge not that you be not judged. Lincoln, having of course delivered a devastating judgment, moderates the Gospel to the gentler assumption of shared responsibility implicit in first person plural: Judge not that we be not judged.

In the spirit of the Temperance Address, Lincoln expresses himself morally without moralizing, noting that the prayer of neither side has been “answered fully.” Then the key: The hard edge of reason in earlier addresses has given way to a prudent respect for what sounds very much like Divine grace. “The Almighty has His own purposes. ‘Woe unto the world because of offences! for it must needs be that offences come; but woe to that man by whom the offence cometh!’” Again the reference is to the Gospel of Matthew. This is neither determinism, it bears emphasis, nor philosophical necessity. Man is responsible for his actions even as he is an instrument of God. The offense was going to happen; the sinner did not have to choose to be its particular causal agent. Indeed, Lincoln immediately casts the war as the due punishment of North and South: the South for its embrace of slavery, the North not just for its tolerance of but also for its interlocking gains from the evil institution.

We hope and pray, Lincoln notes, for a quick end to the conflict. “Yet,” in perhaps the most rhetorically gifted turn of the address, a sentence that could not be diminished or distended by a single word, “if God wills that it continue, until all the wealth piled by the bondsman’s two hundred and fifty years of unrequited toil shall be sunk, and until every drop of blood drawn with the lash, shall be paid by another drawn with the sword, as was said three thousand years ago, so still it must be said, ‘the judgments of the Lord, are true and righteous altogether.’”

The reference is to Psalm 19. The full verse refers not just to the righteousness of the Lord but also to “the fear of the Lord.” And indeed this is a fearful expression of principle, for God exacts retribution for its violation. As Reinhold Niebuhr teaches in his magisterial reading of the Second Inaugural, we see imperfectly yet must judge as best we can. Lincoln’s faith does not justify quietism. It does not reflect determinism. Rather, it guides resolve.

This limited knowledge yet determination to work within it defines the justly famous closing sequence of the Second Inaugural, which once more mitigates severity with warmth: “With malice toward none; with charity for all; with firmness in the right, as God gives us to see the right, let us strive on to finish the work we are in….” Lincoln claims no crystalline clarity of perception as to the right: We see it “as God gives us” to see it—in other words “to the extent” God allows us to see it. This humility is part of the essence of prudence, for Lincoln’s modesty does not imply vacillation. To the extent that we see the right, we are firm in it. This is principle. Prudence governs it by acknowledging the limits of what we are permitted to see.