The choice of León is in keeping with recent history, in which inaugural prayer leaders are Christians, and Protestant Christians at that.* In 2009, TIME magazine noted a surprising exclusion: no rabbis had stood on the inaugural stage since 1985. Ronald Reagan was the last president to hear a Hebrew blessing the day he took the oath of office. Since then, only Protestants have offered prayers from the dais. At “the most anticipated Inaugural Address since John F. Kennedy,” TIME’s Amy Sullivan wrote in 2008, where audiences would hear from Aretha Franklin, Yo-Yo Ma, and preacher Rick Warren, “there’s one thing they won’t hear: Baruch Atah Adonai Eloheinu Melech ha’olam.”

When did Americans first hear Hebrew at a presidential inauguration? It was at the swearing-in of John F. Kennedy, the first Catholic president of the United States (a victory that poet Robert Frost called “a triumph of Protestantism—over itself”). Kennedy had invited Rabbi Nelson Glueck to pray. As the president of the Reform movement’s seminary in Cincinnati, Glueck was a leader of American Jewry, and his archeological scholarship had earned him international renown. With a Roman Catholic elected to the nation’s highest office and a rabbi by his side, the 1961 inauguration represented the apogee of what theologian and sociologist Will Herberg deemed to be a tripartite nation, where, “[b]y and large, to be an American today means to be either a Protestant, a Catholic, or a Jew.”

Glueck was not the first rabbi to recite a prayer at a presidential inauguration. That honor went to President Truman’s old friend Rabbi Samuel Thurman, in 1949. In fact, all of the post-WWII inaugurations from Truman to Kennedy included rabbis’ prayers. Glueck’s participation, however, was notable for his use of Hebrew; the rabbi recited the priestly blessings in their original language. It is a detail of American religious history that has been largely ignored, but it provides insight into Judaism’s position in the late 1950s and early 1960s.

Like the president, Glueck had the kind of good looks that seemed earmarked for the age of television, particularly as Kennedy’s was the first inauguration to appear on color television. Tall and clean-shaven, Glueck bore little resemblance to stereotypical images of traditional rabbis in beards and black garb. He looked more like the kind of Jew who could easily assimilate into gentile society. “Handsome” and “Adonis” were not uncommon descriptors among those who knew him, and his appearance on national television elicited similar remarks. After the inauguration, one supporter from Illinois wrote the rabbi to say, “The only thing that looked prettier was my sail boat.” He added, “When are you going into the movies?” Iphigene Hays Sulzberger—the wife of the publisher of The New York Times—was equally overt in her admiration. “This is a fan letter—just to tell you again how pleased I was that you should have been invited as a representative of the Jewish citizens of the United States to give the benediction at the inauguration. … My secretary, Miss Wilson tells me that your benediction was by far the best of the four prayers and that you looked very handsome.”

He may have looked the part, but Nelson Glueck did not stay on script. None of the other three participating clergy, including the Roman Catholic priest Cardinal Cushing and the Greek Orthodox Archbishop Iakovos, spoke foreign languages in their prayers, but when Rabbi Glueck offered a prayer for the country, he switched from English to Hebrew for the priestly blessings. Footage shot by an unknown news agency (housed at the American Jewish Archives in Cincinnati, Ohio) shows a startled Jackie Kennedy. The look of shock that passed over the First Lady’s face suggests that Glueck’s Hebrew benediction was both unexpected and considered unseemly. In her reaction, Mrs. Kennedy—an exemplar of social behavior in her time—expressed the limits of religious pluralism.

Despite the presence of four clergymen at the 1961 presidential inauguration, religion was still considered a private affair. John F. Kennedy had made just that point in his famous 1960 campaign speech before the Greater Houston Ministerial Association. “I believe in an America where the separation of church and state is absolute, where no Catholic prelate would tell the president (should he be Catholic) how to act, and no Protestant minister would tell his parishioners for whom to vote,” Kennedy said. World War II may have been fought in part to protect religious liberties, but religion was not expected to make too bold or distinctive an appearance, lest it disrupt the ideal of national brotherhood among Americans of all faiths. What was held in common by Protestant, Catholic, and Jew was to be accentuated in the postwar Judeo-Christian tradition.

Although non-Jewish reactions to Nelson Glueck’s inauguration participation are largely missing from the historical record, American Jews praised the moment. “I was on the stand directly opposite you and listened to you with great pride,” attorney Irving M. Engel wrote to Glueck after the ceremony. “Many of us derived satisfaction from the fact that—probably for the first time in history—the Hebrew language was used as part of the Inauguration of the President of the United States.” Irving Jay Fain, a Jewish businessman and philanthropist from Rhode Island, was taken with Glueck’s recitation of Hebrew: “Your use of the original Hebrew of the priestly blessing (irrespective of the exact words) had two extra benefits in reminding the non-Jews of America of the origin of this prayer and of their religious heritage; also of demonstrating to our own Jews the significance and propriety of the original Hebrew in prayer.” Glueck could have had a hand in showing that Judaism was at the root of the American religious heritage; that it was still a living tradition and that its language was far from dead; that Reform Jews were moving toward a re-embrace of ritual; and that even a Jew as capable of acceptance by gentile society as Nelson Glueck wanted to speak it.

Although largely unmentioned in the annals of history, the Hebrew episode at President Kennedy’s inauguration is significant for what it reveals about the nature of postwar American religion and the specific case of Judaism’s rapidly evolving status during this era. “America is a Protestant country,” President Roosevelt told members of his administration in 1942. “Catholics and Jews are here under sufferance.” How different things looked less than twenty years later when a Catholic was elected president and a rabbi’s presence at a presidential inauguration had become commonplace.

And, half a century later, where do we stand in terms of clerical representation? The 2013 inauguration seems far less “post-Protestant,” to use Robert Frost’s terminology, than “all-Protestant.” Fifty years ago, America called itself a Judeo-Christian country, though some at Kennedy’s inauguration still expressed shock when the “Judeo” portion dared to speak its own language. This year, with only one faith tradition represented on the inauguration stage, no one will have to pretend that all blessings are welcome. And that is clearly a missed opportunity for inclusion. How could we think that Protestants have a franchise on national prayers, like “God Bless America”? In fact, that song was written by an immigrant Jew.

Rachel Gordan is a postdoctoral fellow in American Judaism at Northwestern University. She received her Ph.D. in 2012 from Harvard, and is working on a book about postwar American Judaism.

*This post was updated after CNN first reported that the Rev. Luis León would replace Giglio.