Originally published on the CNN Belief Blog.

Editor’s Note: Joseph Loconte, Ph.D., is an associate professor of history at The King’s College in New York City and the author of The Searchers: A Quest for Faith in the Valley of Doubt.

When Barack Obama is publicly sworn in for the second time as president on Monday, he will use two Bibles. One belonged to the Rev. Martin Luther King, Jr., the other to Abraham Lincoln —two of the most religious figures in American political history. Both men saw clearly the moral contradictions that tore at the fabric of American democratic life. Yet both also believed deeply in the exceptional character of the United States and the spiritual significance of its democratic mission.

In a speech to the New Jersey legislature on his inaugural journey to Washington, February 21, 1861, Lincoln reflected on Trenton’s heroic role in America’s fight for independence:

“I recollect thinking then, boy even though I was, that there must have been something more than common that those men struggled for; that something even more than National Independence; that something that held out a great promise to all the people of the world to all time to come.”

Lincoln never doubted the universal appeal of the nation’s experiment in self-government, a “promise to all people of the world” that would endure across the centuries. Unlike modern liberals, Lincoln was no cultural relativist: He believed firmly in natural and inalienable rights that belonged to all people, from every corner of the globe, by virtue of their common humanity. Despite the cancer of slavery and racism that had infected the body politic, no nation was more devoted to securing those rights than the United States. Indeed, Lincoln insisted that America had a God-given role in advancing this cause in the world:

“I am exceedingly anxious that this Union, the Constitution, and the liberties of the people shall be perpetuated in accordance with the original idea for which that struggle was made, and 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.”

Lincoln’s description of America as an “almost chosen people” captured brilliantly the qualified and uncertain character of the nation’s democracy: deeply and grievously flawed, but nonetheless caught up in the righteous purposes of God. Unlike many of his religious contemporaries, Lincoln stopped short of identifying America as the new Israel; no spiritual covenant between God and the United States could be presumed. Lincoln well knew the capacity of religious zeal to poison our politics. Nevertheless, he insisted that America’s commitment to liberty and equality was consistent with the character and intentions of the Almighty.

Martin Luther King, Jr., a Baptist minister, shared Lincoln’s political theology. In a way that many liberal and secular-minded Americans would now find offensive, King wielded passages and principles from the Bible like an ax to assault the racist assumptions that degraded the lives of millions of African-Americans. Like Lincoln, he appealed to America’s spiritual legacy in order to renew its democratic mission.

In “Letter from the Birmingham Jail,” King complained that African-Americans had been denied “our constitutional and God-given rights.” He declared that “the goal of America is freedom,” a mandate from heaven itself. Indeed, King saw the hand of God in the political fight to call America back to its founding ideals: “If the inexpressible cruelties of slavery could not stop us, the opposition we now face will surely fail,” he wrote. “We will win our freedom because the sacred heritage of our nation and the eternal will of God are embodied in our echoing demands.”

Modern liberalism scorns the very idea of “the sacred heritage of our nation.” It rejects the view of America as “an almost chosen people,” an exceptional nation devoted to political and religious ideals anchored in a transcendent cause. In this sense, Mr. Obama’s party, the party of liberalism, would not know what to do with a Lincoln or a King.

It is heartening, and symbolically important, that Mr. Obama will be using the Bibles of these two great leaders as he takes the oath of office. It would be more significant, though, if the president found room for their moral vision of the United States in his administration and in his party.