Beginning in the 1920s, American religious liberals borrowed language from the social sciences to describe the social experience of religion. Wishing to foster tolerance at a time when ethnic hatreds increasingly controlled world politics, they tried to drop the word “race” as the equivalent for a religious community and instead depict religions as cultural units by substituting terms like “group.” This was part of a broad intellectual transition in the free West. Long-standing biological models of society, assuming racial differences, gave way to explanations of human behavior emphasizing acquired traits. In this way, democratic cultures, confronting fascism, reaffirmed the malleability and equality of peoples and rejected determinism and hierarchy. American religious liberals of Protestant, Catholic, and Jewish backgrounds, committed to ecumenism and attentive to secular ideas, readily appropriated the new idiom. By the 1940s, talk of Nordic, Celtic, and Jewish races, among others, was rare, and the three mainstream religions, pictured as bearers of values, were praised as democracy's building blocks. Yet, because religion serves private needs and transcendent aspirations as well as society, this romance with social-science functionalism was short-lived. It was a small step from lauding religions as comparable and compromising to missing their distinctiveness, and a mood of traditionalism, expressed in humanistic, often biblically informed words, gained ground after World War II. This was not a simple speech revolution, however. Rhetoric that cast religions as social equivalents had enhanced the climate of freedom, to the point that religious minorities re-explored their heritages with unprecedented confidence. Social-science words set stage for their own subversion. This account of linguistic borrowing suggests the utility of considering religion as one language system among others in a complex culture. In this view, religious rhetoric is a public embodiment of values situated to interact with secular speech, making word use a sensitive meter of religious transformation.