One hundred fifty years ago this week, on March 4, 1865, Abraham Lincoln delivered his Second Inaugural Address ­— almost certainly the strangest and most philosophically challenging political speech in American history.

The anniversary is worth marking, not least because Lincoln’s themes — the role of religion in human conflict; the deep, tragic roots of America’s racial divisions, and the need of forbearance in our national life — don’t seem entirely irrelevant down to this day.

It won’t be long before Americans are assured that the approaching 2016 presidential scramble will be “the most important election in American history.” Every U.S. campaign eventually gets that hard-sell hype.

But such hyperbole makes lousy history — not because any national vote is unimportant, but because it is so indisputable that the most pivotal of America’s elections was the one that put Lincoln on the inaugural platform that rainy March day in 1865.

In 1864, America had conducted a hard-fought national election in the midst of one of human history’s bloodiest civil wars. An exhausted, brokenhearted nation — roughly one in every 10 young adult men died in the conflict — decided nothing less that year than whether to stick with Lincoln and see the horrible struggle through or settle for a negotiated peace that would have perpetuated slavery, dismembered the nation and discredited democracy.

At first, Lincoln seemed sure to be ousted, until long-awaited Union battlefield successes altered the mood. Voters in the loyal Northern states chose to fight on, and by March 1865, total victory at last was near.

It was, in short, a moment of exquisite triumph mixed with bitter hard feeling. Observers looked forward (whether with pleasure or apprehension) to a Second Inaugural Address in which the unyielding war president would celebrate his vindication and promise just deserts for the vanquished traitors in the South who had brought so much misery upon the country.

But that isn’t at all what the country got. Instead, Lincoln delivered a brief, sorrowful sermon on the ultimate meaning of America’s terrible ordeal.

It was “the Almighty,” Lincoln declared, who had imposed the retribution — a “mighty scourge of war” to punish the entire nation, “both North and South” — for the 250-year-old sin of what he pointedly called “American Slavery.”

In his book “Lincoln’s Greatest Speech,” Ronald C. White Jr. describes the large inaugural crowd gathered before the Capitol in Washington, and its forlorn attempts to find applause lines in Lincoln’s mortifying musings.

The closest thing they got to a “Mission Accomplished” moment was when Lincoln pronounced the military situation “reasonably satisfactory and encouraging to all.”

What’s more, even when the speech exposed the wickedness of slavery — “It may seem strange that any men should ask a just God’s assistance in wringing their bread from the sweat of other men’s faces” — Lincoln ruined the effect by quickly admonishing: “but let us judge not, that we be not judged.”

The biblical allusions and deep religious fatalism of the Second Inaugural are all the more fascinating because Lincoln’s spiritual beliefs have always been something of a mystery and controversy. Secular Americans from his day to this have been eager to claim Lincoln as a skeptic about Christianity.

Maybe he was one, but the author of the Second Inaugural was no orthodox materialist.

What Lincoln certainly doubted by the end of the war was human understanding of the will of God. He portrayed Americans, whether striving to save or dismantle their union, as having been controlled by a hidden divine purpose.

“Both [sides] read the same Bible,” he observed, “and pray to the same God; and each invokes his aid against the other.”

That the most sincere beliefs can fuel the most misguided ideas is an insight worth recalling today. So is Lincoln’s warning against ever supposing that one possesses the whole truth.

By the time of the Second Inaugural, White explains, Lincoln had spent years privately trying to come to terms with the shocking price America was paying for the evil of slavery. With the struggle almost over, he called for his countrymen to accept that price as just, even “if God wills that [the war] continue, until … every drop of blood drawn with the lash, shall be paid by another drawn with the sword …”

The war soon ended, but racial injuries, injustices and tensions continued. They persist today.

And maybe Lincoln wouldn’t be surprised that the consequences of slavery and all that followed from it still confound Americans all these generations later.

The best-known and best-loved passage of Lincoln’s Second Inaugural came at the end — expressing what he considered a proper response to the nation’s shared guilt and penance.

White says “an unspoken ‘Therefore’ ” precedes Lincoln’s famous plea that Americans seek peace “[w]ith malice toward none, with charity for all …”

It was too much to ask, of course. Postwar “Reconstruction” in the South would be undermined by corruption, self-righteousness and white supremacist terror. In the audience listening in a rage to Lincoln’s gentle speech was John Wilkes Booth, who would assassinate the president just 41 days later.

But Lincoln’s magnificent language and humble spirit have lived on, and should at least inspire later generations of Americans to keep today’s hardships, and conflicts, in perspective.


Doug Tice is at D.J.