(RNS) — If I were to hold a séance, I’d invite two of my late teachers to the table to ask what they think about the war with Iran.

My first teacher was a Protestant theologian who became one of the most influential public religious thinkers in American history, Reinhold Niebuhr (1892-1971).

Niebuhr served a congregation in Detroit until 1928, when he became professor of practical theology at Union Theological Seminary in New York. UTS is only a few blocks away from the Jewish Theological Seminary, and Niebuhr formed a deep friendship with Rabbi Abraham Joshua Heschel, who taught at that seminary. This caused one Jewish scholar to quip that JTS’ motto could be “love your Niebuhr as yourself.” When Niebuhr died in 1971, Heschel delivered the eulogy.

In an age that preferred comforting illusions, Niebuhr was a moral realist. He taught the idea of “Christian realism,” believing that human beings are morally capable but deeply flawed, so political life requires humility, restraint and sometimes the responsible use of power. He influenced many thinkers and activists, including the Rev. Martin Luther King Jr. and former President Barack Obama.

Niebuhr was the author of the Serenity Prayer, but I think he would have rejected any serenity now. I believe he would see the confrontation with Iran and would repeat one of his central themes. Human societies contain ambition, fear, pride and a relentless struggle for power. That means that there are no perfectly pure choices, and it means leaders must often choose between imperfect alternatives.

He rejected temptations that distort the moral debate about war. First, he rejected naïve pacifism — the belief that goodwill and diplomacy can eliminate violence from history. He argued that the refusal to confront evil can itself become immoral. During the 1930s, when fascism and Nazism arose in Europe, many religious liberals were anti-war. Niebuhr challenged them directly. If tyrannical regimes threaten justice and human freedom, he insisted, responsible nations must resist them, and sometimes with force, he contended.

Niebuhr captured the moral stakes of that struggle in the opening lines of his 1952 book, “The Irony of American History”: “Everybody understands the obvious meaning of the world struggle in which we are engaged. We are defending freedom against tyranny and are trying to preserve justice against a system which has, demonically, distilled injustice and cruelty out of its original promise of a higher justice.”

If Niebuhr lived today, he would likely apply that same sober realism to Iran. “We take, and must continue to take, morally hazardous actions to preserve our civilization,” he wrote. It is necessary to resist, even militarily, a regime that spreads ideological hatred, murders its citizens, screams genocidal plans or threatens regional stability.

But, while tyranny creates moral danger, Niebuhr knew that war does the same thing. Military power can corrupt nations. Civilians die, inevitably. Military victory can lure nations into arrogance. Even righteous causes can produce tragic consequences.

Therefore, in times like these, what should nations do? Use force, yes — but reluctantly, with solemnity, humility and accountability.

My second teacher is Elie Wiesel, winner of the Nobel Peace Prize, author, the most passionate moral witness of our time and the subject of a wonderful new PBS documentary. The young man who survived the Holocaust grew into a man whose life mission was to warn the world about evil and the risk of forgetting. He insisted that humanity must remember what hatred can do.

Wiesel understood something many societies prefer to ignore: evil does not disappear, even if it changes its language, symbols and slogans.

In his 2012 memoir, “Open Heart,” he warned: “But the forces of evil have not abdicated. The malevolent ghosts of hatred are resurgent with a fury and a boldness that are as astounding as they are nauseating.”

For Wiesel, indifference created the greatest moral danger. In his Nobel acceptance speech in 1986, he said: “We must always take sides. Neutrality helps the oppressor, never the victim. Silence encourages the tormentor, never the tormented.”

But, Wiesel never celebrated war. He understood its devastation more deeply than most political leaders ever will. He watched Europe burn. He lost his family. He saw children disappear into smoke.

Wiesel simultaneously demanded both vigilance against evil and compassion for the innocent. He never stopped thinking about victims, especially children. His moral vision constantly returned to the human cost of conflict. As he wrote in “A Jew Today”: “Even in a just war, cruelty is an evil.” 

I sit with my two teachers during these fraught moments in our national and international life, at a time when the United States and Israel are fighting a very controversial war. (I urge you to listen to Haviv Rettig Gur on why this is, in fact, America’s war.) Both rejected naïve innocence and reckless violence alike.

Some question the legality of this war, that Congress did not authorize it. Sometimes a situation requires decisive action. In 1995, during the Srebenica massacre, more than 8,000 Bosnian Muslim men and boys were killed. The failure to stop that atrocity shaped Western thinking about humanitarian intervention and influenced the willingness of the U.S. and its allies to launch NATO airstrikes in Kosovo four years later. It was necessary, and innocent civilians were killed.

Some are naive about the depths of evil in the world. To quote the singer-songwriter, John Martyn, “I don’t want to know about evil; I only want to know about love.”

But we don’t have the luxury of not wanting to know about evil. Iran’s government has been a source of radical evil — which the throngs of jubilant Iranians celebrating after Ayatollah Ali Khamenei’s killing might affirm. But there are also cheerleaders for this war who need a better approach of accountability and humility. And some on both the right and the left prefer isolationism. Some of it is antisemitic — I’m looking at you, Tucker Carlson, with your delusional fantasies that Chabad is behind this war.

Wiesel once told a tale about a man who came to the wicked city of Sodom. He sat in the town square, screaming. Someone approached him and asked, “Do you think that your screaming will change anyone?” His response was, “Perhaps not. But at least, they won’t change me.”

It takes moral courage to not allow the vulgarity and violence of the world to seep into your bones and your soul. I believe my teachers, Niebuhr and Wiesel, would agree.