This paper reexamines the mid-1960s debate between Abraham Joshua Heschel and Joseph B. Soloveitchik over Jewish-Christian dialogue following the Second Vatican Council. While often portrayed as a clash between an open and a restrictive vision of Judaism, the paper argues that the debate must also be understood within the specific context of American Judaism in the Cold War era. Analyzing their writings and newly examined archival material, it shows that Heschel’s support for interfaith dialogue was rooted in a vision of a Judeo-Christian alliance grounded in the Hebrew Bible and united against communist atheism and moral nihilism. Soloveitchik, by contrast, opposed this alliance, fearing it would blur religious boundaries and threaten Jewish distinctiveness within a Christian-majority culture. The debate therefore reflects broader struggles over identity, ideology, and cultural integration in postwar American Judaism.