McKinley's spiritual life and Methodist Christian moorings proved decisive in his determination to launch a humanitarian intervention. Staid and stiff, the president hardly seems religious in contrast to his 1896 electoral opponent, William Jennings Bryan. And compared to his ebullient successor, Theodore Roosevelt, McKinley comes off as boring. In this case, appearances deceive.

The religious equivalent of kudzu, Methodism converted so many nineteenth-century Americans that it became the single largest Protestant denomination in the U.S. Among these converts was a young Will McKinley. A fervently anti-slavery teetotaler, McKinley's inner spiritual world ran hot.

The minister who oversaw his conversion and baptism actively worked in the Underground Railroad, while his hometown, Poland, Ohio, was a veritable hotbed of abolitionist sentiment. The self-described "soldier of Jesus" who served in "the psalms-singers of the Western Reserve" during the Civil War very much embodied mainstream liberal Protestantism.

In American politics, "mainstream" is often synonymous for banal. Anything but lackluster, Gilded Age Protestants boasted a worldview rife with messianic visions, which effectively updated the sacred-secular mission for a new era. Indeed, one leading proponent of an interventionist foreign policy, Josiah Strong, claimed his generation's actions would "hasten or retard the coming of Christ's kingdom."

Reflecting the destinarian imprint, liberal Protestants, including McKinley, pushed for humanitarian interventions as an expression of America's sacred-secular project. Not coincidentally, in the late nineteenth century Americans took the lead in establishing foreign missions and tending to the needy across the seas. Strong, for one, called for Americans to Christianize the world.

It was at this crucial historical juncture that Americans pushed their nation to stanch Spain's bloodletting in Cuba. In due course, humanitarian calls for intervention convinced the president to act.

The Maine's explosion is rightly credited with rousing mass sentiment for war. However, elite opinion regarding the humanitarian situation in Cuba was much more significant in shaping McKinley's policy than headlines in the penny press. Disregarding pro-war hysterics from the start, it was the first-hand reports from Clara Barton and Senator Redfield Proctor which proved decisive.

The latter's fact-finding trip to Cuba reveals the central role humanitarian concerns played in McKinley's decision for war. The senator's visit and interventionist bent hardly made him distinct. Nonetheless, his conservative bona fides, perceived relationship with the president, and sense of drama rendered his pronouncement a political bombshell.

After visiting the island, Proctor refused all interview requests. Instead, he penned a simple "statement" which he planned to deliver to the Senate.

Proctor dramatically took the senate floor before a packed gallery, describing the "desolation and distress, misery and starvation" that was Cuba. Proctor's speech rallied the business community and wary business journalists to combat the humanitarian nightmare.

Convinced that "an American Armenia" was festering 100 miles away, the Wall Street Journal and the New York Commercial Advertiser threw their weight behind intervention. McKinley called for war to "put an end to barbarities, bloodshed, starvation, and horrible miseries now existing there."

For decades, historians dismissed this rhetoric as insincere cornpone. Hardly deceitful, McKinley's humanitarian motives and religious hubris led him to war while also blinding him to the dangers of its aftermath.

Twentieth-Century Humanitarian Interventionism and Rienhold Niebuhr

In the years following the Spanish-American War, the Social Gospel movement animated U.S. foreign policy. Looking to ameliorate domestic and foreign ills, American Progressives also heeded the sacred-secular mission.

Confident that their new millennium still beckoned, many Progressives backed American entry into World War I as a vehicle to "end all wars and institute world democracy." The wartime experience and postwar peace, however, destroyed their hopes that military engagements could achieve millennial results.

Consequently, interwar Progressives and religious liberals largely embraced pacifism. This antiwar bent hardly negated all international humanitarian endeavors. Following his famine relief efforts in Belgium in 1921, Herbert Hoover organized a massive food drive for the Soviet Union, honoring the sacred-secular mission even as pacifism crested.

By the 1930s, most mainline liberal Protestants had accepted the Social Gospel's newfound antimilitarism. Yet in the face of fascist aggression and Soviet brutality, Niebuhr pioneered a fundamental rethinking of liberal Protestantism's stance toward world events. Attacking a "Christianity that suffers from modern liberal illusions," he maintained that in certain instances pacifism represented a greater evil than intervention and war.

With humanity's inherent sinfulness rendering millennial progress moot, the theologian opted for chastened domestic and foreign policy goals. The archetypal realist nevertheless remained unwittingly committed to the sacred-secular charge.

Developing a more refined and sophisticated version of the American mission, Niebuhr claimed God had chosen the U.S. to defend "Western Civilization." All the same, he fundamentally rejected any nation or ideology's claim to transhistorical meaning. In other words, Niebuhr might have embraced America's "chosenness" but he contended no individual or nation could fully act immanently.

Niebuhr would only support humanitarian intervention, or any foreign policy venture, under certain circumstances. Recognizing that nations act from self-interest and individuals discern their motivations only with extraordinary difficulty, if at all, Niebuhr called for multilateralism.

With allies better able to detect hidden, selfish motives within their partner states, the theologian reasoned America could maintain its "responsibility" to the world, while restraining its messianic passion and inherent sinfulness.

In a stark about-face from their Social Gospel brethren, Christian Realists not only backed American nuclear policy, they also supported Truman's Cold War policies.

The Soviets might have required containment, but for Niebuhr, any superpower utterly convinced of its transhistorical role presented an international danger. In this way, Niebuhr's brand of liberal Protestantism offered a necessary rein upon on Americans' destinarian fervor.

The theologian's restraints came none too soon. Whereas the founders envisioned their democratic experiment as world altering, they possessed little power to pursue their grand project. The geopolitical equivalent of a Chihuahua, few, if any, world leaders much noticed the infant republic's braggadocio. One hundred and seventy years later, however, America's greatly enhanced power rendered its sacred-secular missionizing a global concern.

Once engaged in a global struggle against the Soviets, American policymakers inevitably overreached. From CIA-backed coups to Vietnam, the potent cocktail of power politics, self-interest, and destinarian passion produced bad and, at times, immoral decisions.

Attempts to remove humanitarian concerns from U.S. policy proved futile. Richard Nixon and Henry Kissinger's realism effectively united conservatives, neo-conservatives, and liberals in their contempt for détente. As a result, disparate politicians—from Jimmy Carter to Henry Jackson and Ronald Reagan—made "human rights" central to their foreign policy worldviews.

In the early post-Cold War world, America possessed a relatively free hand in global affairs. Not surprisingly, the 1990s witnessed an abundance of U.S.-led humanitarian interventions. From Somalia and Bosnia to Kosovo and the Iraq War, Republican and Democratic presidents looked abroad to channel the sacred-secular mission. Producing uneven results, humanitarian interventions lacked sound guiding principles.

Barack Obama's Humanitarian Intervention

The key to understanding President Obama's foreign policy lies with Niebuhr. In 2007, New York Times columnist David Brooks accidentally discovered Obama's inner Niebuhr. Searching to enliven a limp interview, Brooks asked the senator-cum-presidential-candidate, "Have you ever read Reinhold Niebuhr?" The candidate vigorously recounted The Irony of American History's basic argument.

Two years later, the president's connection to a then-obscure thinker had faded into little more than a campaign footnote. The president's Nobel Peace Prize prompted the association's return. An obvious commentary on George W. Bush's pervasive unpopularity rather than Obama's accomplishments, the Nobel gave the newly inaugurated president a global stage from which to announce his worldview. Obama's address walked a precise Christian Realist line, verging on theological.

Pronouncing war and violence "a fact" of human existence emanating from "the core struggle of human nature," Obama struck a realist note. Hardly a latter day Kissinger, the president still endorsed robust action to improve the world but warned, "We are fallible. We make mistakes, and fall victim to the temptations of pride, and power, and sometimes evil." The address echoed Niebuhr's tragic sense of history and human nature.

An unlikely liberal Protestant and Niebuhrian, Obama grew up without organized religion. Exposed to a multiplicity of faiths and creeds in Hawaii and Indonesia, the president only found God as an adult.

Constantly in and out of Chicago's black churches while working as a community organizer, Obama discovered faith at Jeremiah Wright's Trinity United Church of Christ. The predominately white, liberal Protestant denomination had established a parish on Chicago's south side in the late 1960s. Derided as a "white church in black face," Wright quickly made the institution respond to the spiritual and political needs of Chicago's educated, black middle class.

A Christian whose first church community emphasized social action and the "audacity of hope," Obama's newfound spiritual life merged with his careful intellect. The Harvard-trained lawyer renowned for his ability to synthesize seemingly incongruous arguments brought these skills to his religious life.

In this context, Obama's attraction to Niebuhr appears quite understandable, even predictable. Like the president, the neo-orthodox, liberal Protestant also synthesized incompatible ideas and impulses.

The United States and Libya

Organizing an international response to Qaddafi required deft and original thinking. A regional menace and certified megalomaniac, Qaddafi had distinguished himself in a region dominated by autocratic sadists. Moreover, his bloody crackdown on his corner of the Arab Spring forced the president to confront the Niebuhrian "core struggle": doing right without arrogantly doing too much.

When Qaddafi first began slaughtering innocents there hardly seemed much of a policy or moral struggle in the administration. With the vice president, secretary of state, defense secretary and national security adviser preaching restraint, intervention appeared unlikely.

In early March, Robert Gates publicly wondered whether American participation in an Arab League no-fly zone would be a "wise thing to do." From the mouth of the famously understated defense secretary, the oblique comment sounded like definitive policy. Indeed, Qaddafi's terrorist past and penchant for bizarre behavior were mitigated by Libya's oil reserves and recent détente with the West.

Political realists offered sound arguments against removing Qaddafi. If Libya's uprising had emerged outside the Arab Spring's timeframe, Gates probably would have prevailed.

Caught flat-footed by the Arab Spring, Obama struggled to balance the region's democratic aspirations with short-term American interests. After belatedly calling for Hosni Mubarak's ouster, Hillary Clinton found herself on the wrong side of the generational and political divide. Clinton realized, "We didn't get off to such a great start with Egypt—let's reverse that with Libya."

Others in the administration shared similar views. Susan Rice, appointed by Obama as U.S. ambassador to the United Nations, still agonized over her role in the Clinton administration's dithering in Rwanda. Claiming she would rather see her career "go down in flames" than America sit idly by during another genocide, Rice looked to Libya for redemption.

With the Arab Spring producing tectonic shifts in the region's politics and Qaddafi's forces moving toward Benghazi, Clinton, Rice, and others backed intervention. Their combined bureaucratic heft and strategic argumentation, along with the president's own inclinations, proved decisive.

Echoing a much-tempered version of the sacred-secular project, Obama explained his intervention in a televised address: "To brush aside America's responsibilities as a leader and—more profoundly—our responsibilities to our fellow human beings under such circumstances would have been a betrayal of who we are. Some nations may be able to turn a blind eye to atrocities in other countries. The United States of America is different."

Somewhere, William McKinley must have been smiling.

Still more hammer than scalpel, humanitarian interventionism remains a decidedly perilous foreign policy tool. Shorn of sound strategy and moral principles, it can easily produce imperialist or destabilizing results.

Lacking Arab unity and an impending Benghazi-like massacre, Obama has, thus far, resisted intervention in Syria. The sacred-secular mission in concert with popular pressures and changed circumstances could very well prompt American intercession.

Indeed, the combination of power, religious thinking, and ongoing atrocities leaves the possibility of a U.S.-led humanitarian intervention as likely an option as it ever was.