Mordecai Kaplan's Judaism as a Civilization (1934) is most often read as Kaplan's effort at a rapprochement between Judaism and America. In contrast to conventional readings of that work, this article highlights Kaplan's suspicion of America, and liberal modernity more generally, by engaging with his analysis of the categories of religion and race. Kaplan, I argue, is haunted by the prospect that in adopting either of these categories, American Judaism will surrender its particularity and collectivity to the liberal, ultimately Christian, state. Indeed, in his own context, Kaplan considered Reform Judaism to be proof of the perils of Jewish accommodation of either category. The article attends to Kaplan's analysis of religion and race as an unlikely resource for thinking through a number of contemporary issues with respect to religion, race, and Jewishness in American life. I argue that Kaplan's anxieties about Christianity and modern liberalism demonstrate a striking prescience about the denaturing of American Judaism in its being annexed to whiteness. The article puts Kaplan into conversation with James Baldwin, who clearly saw Jewish whiteness as yet another casualty of conquest by that “old, rugged Roman cross.” Finally, Kaplan's comments in Civilization about anti-Black racism are few. Read together with his diary, however, they evince sensitivity to the religious constraints put on Black life in America. This article thus concludes by putting Kaplan in conversation with Sylvester Johnson's work on “Black ethnics” and Judith Weisenfeld's research on “religio-racial movements.” This engagement suggests that Kaplan's analysis is not specific to Judaism only, but is more broadly related to the issue of how the modern logics of religion and race continue to discipline expressions of otherness that do not abide by the boundaries of these categories. Kaplan thus contributes an important Jewish vantage on the continued over-determination of American religious life by white Christianity.