The answer according to all sources consulted is a resounding “yes,” they were both friends and colleagues.
They met in January 1963, at the Chicago conference on “Religion and Race” organized by the National Conference of Christians and Jews, and became immediate friends. Dr. King’s speech included “The churches and synagogues have an opportunity and a duty to lift up their voices like a trumpet and declare unto the people the immorality of segregation.” Rabbi Heschel’s speech began:
“At the first conference on religion and race, the main participants were Pharaoh and Moses…. The outcome of that summit meeting has not come to an end. Pharaoh is not ready to capitulate. The exodus began, but is far from having been completed. In fact, it was easier for the children of Israel to cross the Red Sea than for a Negro to cross certain university campuses.”
As Dr. King encouraged Rabbi Heschel’s participation in the Civil Rights movement, Rabbi Heschel encouraged MLK to take a stance against the war in Vietnam.
The two revolutionaries apparently shared a similar take on religion as well as civil discourse. Both had conservative religious upbringings enhanced by theological education among reformists. Heschel, born in 1907 into a multi-generational Chassidic family in Warsaw, studied at the Hochschule für die Wissenschaft des Judentums (the Reform movement’s seminary) in Berlin. King, born in 1929 into an Atlanta family of ministers, attended the Ebenezer Baptist Church (where his grandfather Rev. A.D. Williams was pastor), and then studied at the liberal Protestant Crozer Theological Seminary. Heschel earned a doctorate in philosophy at the University of Berlin, and King completed his similar doctorate at Boston University.
Both men found that their social consciousness informed their religiousness, and vice-versa. They spoke at the same conferences more than a few times, and when MLK spoke at the United Synagogue of America’s Golden Jubilee Convention in 1963 in New York, he talked about the oppressed “brothers and sisters who happen to be Jews in Soviet Russia.” MLK felt that “injustice anywhere is a threat to justice everywhere.”
On March 21, 1965, Heschel answered the call for religious leaders to join the march from Selma to Montgomery for voting rights. The night before the march, many of the leaders were guests at the same home. In the morning they were found each in his corner of the house saying morning prayers. The two friends marched together and crossed the Edmund Pettus Bridge arm in arm. Heschel found it to be a spiritual experience, and later said he felt his “legs were praying.”
Both men spoke against the Vietnam War at Riverside Church on April 4, 1967, Heschel following King and ending with “I conclude with the words of Dr. King: ‘The great initiative of this war is ours. The initiative to stop it must be ours.’”
Dr. King once said of his friend, “Rabbi Heschel is one of the persons who is relevant at all times, always standing with prophetic insights” to guide persons with a social consciousness.
According to Rabbi Heschel’s daughter Susannah, her father came to this calling naturally. When he arrived after fleeing pogroms, the local Yiddish newspapers were reporting loudly about the pogroms here, in the United States, referring to the lynchings of black persons. Jews are taught that we do not look the other way, we act.
The relationship came to an abrupt finality shortly after Dr. King spoke in 1968 at a celebration of Rabbi Heschel’s 60th birthday organized by the Rabbinical Assembly of America: Dr. King was murdered ten days later.
Rabbi Heschel spoke at his funeral. He included these words: “Martin Luther King is a voice, a vision and a way. I call upon every Jew to harken to his voice, to share his vision, to follow in his way. The whole future of America will depend upon the impact and influence of Dr. King.”