The growth of religious disaffiliation in the United States over the past three decades is historically unprecedented. This article argues that disaffiliation is a form of moral protest against lingering coloniality in American global North Christianities and appeals for missiologists to adopt a decolonial lens to more effectively critique harmful religious systems and investigate exterior forms of Christianities otherwise in the North American context. The article explores existing sociological and empirical data on disaffiliation, deconversion, and religious harms to expose the moral protest of disaffiliation. Decoloniality is distinguished from postcolonialism to reveal its relevance for the subject matter and identify its method. Using examples of North American missiologies, the article demonstrates how latent forms of coloniality are preserved despite decolonizing efforts in the field and how a decolonial lens can bring new works of the spirit into focus. Finally, it briefly explores implications for future research.