Histories of European immigration to the late nineteenth century United States have emphasized vectors of acculturation such as language, socioeconomics, and ethnicization. And the emerging field of “whiteness studies” has convincingly pointed out the malleability of racial categories that were contingent on the legal and cultural power structures in which immigrants found themselves. However, the degree to which religion could define cultural whiteness beyond its traditional locus among WASPs and function as an agent of acculturation remains largely underexplored. This article traces the efforts of Anglo-American Protestants to recruit actively “desirable” immigrants from Northern Europe and the opennness of these immigrants to utilize religion as a fulfillment of racial promise. Taking the story of such immigrants among Chicago Anglo-Protestants as a case study, I argue that while factors of race and language could play a role, religion is the crucial link missing from current and ongoing efforts to outline the cultural whiteness that qualified good Americans.