Given the Trump administration’s ambiguous approach to religion discussed in the previous chapter, Chapter 15 explores how American Christians have reacted to it. It finds that although there initially appeared to be a certain level of religious immunity among practicing Christians against Trumpism, this religious ‘vaccination effect’ against national populism has since diminished and even reversed to the extent that, unlike in Europe, American Christians have become one of the populist right’s most loyal constituencies. American Christians’ ‘conversion’ to Trump appears, however, to be less the result of a shift in their attitudes than of supply-side factors. Specifically, a perceived lack of political alternatives as well as the inability and unwillingness of Christian leaders to publicly speak out against Trumpism seem to have contributed to this development.