This week I reported on the role Jews played in the civil rights movement under Martin Luther King. It’s a fascinating story, and one that many people I interviewed told me remains poorly understood. Often it’s reduced to a glib one-liner: Jews supported him, a line captured best by the iconic image of rabbi Abraham Joshua Heschel walking with King in from Selma to Montgomery in 1965. But the relationship between King and Jewish leaders far preceded the one with Heschel, however important it was. And the Jewish community’s relationship was far more varied and complicated than that image allows. Read the full story here.

But there were some other points I had wanted to highlight that I didn’t have enough space to include in my story. So I’ll do it here. JTS Chancellor Arnold Eisen focuses on one of them in his own story in our paper: the crucial theological connection that undergirded Heschel and King’s bond.

It also points to the broader issue I wanted to raise: King’s religiosity. His deep religious convictions are usually relegated to a sideshow in the santized history we learn in grade school. But that’s a serious omission, since at root King was a preacher. And he believed the civil rights movement was an expression of God’s will. Moreover, King’s religious beliefs were rooted in his tremendously rigorous education; the "Dr." in his name is significant, affixed after he got his Ph.D. in theology from Boston University.

No doubt the most significant thinker on King’s theology was Reinhold Niebuhr. At midcentury Niebuhr was not only Christianity’s most prominent liberal theologian but also a profoundly influential public intellectual to boot. (Barack Obama and David Brooks are big fans too.) Niebuhr’s classic "Moral Man and Immoral Society" (1932) set King on fire when he first read it at seminary, and throughout his time at Boston University, he wrote a number of papers on Niebuhr’s work, even beginning a correspondence with Niebuhr for help on his dissertation.

For King, Niebuhr’s central insight–now called Christian realism–was that evil was a fundamental part of human nature. It could only be eradicated by recognizing that fact and acting on man’s better angels to combat it. For King, God manifest himself in the world through man’s positive actions. To act was to be godly.

Niebuhr’s philosophy was a direct attack on the main liberal theology of his time, called the Social Gospel. Niebuhr, and King after him, argued that Social Gospel types were too naive and idealistic. Their insistence that man was fundamentallly good paralyzed liberals into accepting the status quo. As King would later summarize, Niebuhr’s appeal was that he understood ‘‘the false optimism characteristic of a great segment of Protestant liberalism." In contrast, he wrote, Niebuhr’s own theology provided "‘the necessary corrective of a kind of liberalism that too easily capitulated to modern culture’’

In the real world, Christian Social Gospel believers found common cause with secular liberals, fusing their ideas into another naive composite notion: that man could be reasoned out of immoral acts. For Niebuhr, who had lived through the Second World War, that was a hopelessly naive, immoral even, as it too often led to inaction in the face of injustice. We first had to open our eyes the subtler manifestations of evil in the world, Niebuhr argued. Only then might we be able to act forcefully against it.

That explains the militancy of King’s activism, another fact we conveniently ignore when talking about King. Of course King’s militancy was, crucially, wedded to Ghandi’s precept of nonviolence. But King even went so far as to dub his own brand of activism "nonviolent militancy," a kind of rhetorical goad to action. King believed wholeheartedly in racial harmony, peace and justice — all the good things liberals love. But he felt there was only one way to attain those things when faced with a world constantly corrupted: forceful, albeit nonviolent confrontation. Sit-ins, lawsuits, boycotts, protests, open letters, op-eds, marches: that’s how you did it.

This kind of amalgation of disparate intellectual sources–Ghandi, Niebuhr, bits of the Social Gospel here, some St. Auqinas there, Heschel, Buber–is what made King such a commanding force. His oratory and actions impacted millions, but his intellectual scrupulousness made the educated elite–lawyers, politicians, academics, clergy–take him seriously.

It’s why Heschel did too. Like Niebuhr, Heschel believed in a sort of "Jewish realism." Evil did exist in the world and it was man’s religious and moral obligation to combat it. Moreover, Heschel’s book on the the Prophets, based on his own Ph.D. thesis at the University of Berlin, had an important impact on King. The role of the prophet throughout Biblical history, Heschel argued, was to critique his own society when his community betrayed God’s will.

Heschel also subscribed to the Kabbalistic notion that God was actively engaged in the world–in stark contrast to the commonly held notion that God had fled from it after He created it. Many rabbis had been arguing that God had effectively removed himself from the world after its beginning, which was a particularly attractive notion in light of the Holocaust. After all, how could God be in a world and allow such horrors?

Heschel said horrors happened not because God abandoned us but because we abandoned God. And because God was had more human attributes than traditional Jewish theology allowed–namely, He felt the pain of human suffering as much as humans did–to let evil exist in the world was also to hurt God too. Religious leaders therefore had a religious obligation to fight injustice anywhere they saw it.

This was the prophetic tradition. And it is therefore not surprising to learn that King used Heschel’s own translation–not the King James’ Bible version–every time he quoted Amos, one of King’s most frequently quoted Biblical figures. "Let justice roll down like waters and righteousness like a mighty stream," was how Heschel translated Amos. King liked that.

It is also not surpising to learn that Heschel and Niebuhr were lifelong friends. The two would often walk to their respective seminaries together on the Upper West Side–Heschel to the JTS, Niebuhr to the Union Theological Seminary next door.

There is even a story I find particularly touching about them. In the early ’60s, Heschel went to Rome to advise the Pope on his impending decision to officially absolve Jews for the death of Christ, which would become the crux of Vatican II. Heschel brought back a bottle of brandy for Niehbuhr and left it with the doorman of Niebuhr’s Riverside Drive apartment.

The Niebuhr’s got it late Friday afternoon and, just before Reinhold’s wife Ursula called to thank Heschel, she hung up the phone. It was almost Shabbat, she thought; he wouldn’t pick up.

Then the phone rang. "Abraham!" Ursula yelled. "I was going to ring you up to thank you, Reinhold is right here, but the sun has set."

"It is all right. There are two more minutes to go," Heschel replied, adding: "I wanted to be sure."