This book raises the question of what an Indigenous church is and how its members define their ties of affiliation or separation. Establishing a pioneering dialogue between Amazonian and Gran Chaco studies on Indigenous Christianity, the contributions address historical processes, cosmological conceptions, ritual practices, leadership dynamics, and material formations involved in the creation and diversification of Indigenous churches. Instead of focusing on the study of missionary ideologies and praxis, the book explores Indigenous peoples' interpretations of Christianity and the institutional arrangements they make to create, expand, or dismantle their churches. In doing so, the volume offers a South American contribution to the theoretical project of the anthropology of Christianity, especially as it relates to the issue of denominationalism and inter-denominational relations.