The history of Christianity in Amazonia until the present day is replete with controversies and negotiations over right kind of Christianity. Missionaries representing a variety of different denominations have considered local indigenous forms of Christianity as inauthentic. The question of real Christianity has also coloured local level inter-denominational relations and led to ruptures in social cohesion. Grounded in ethnographic fieldwork among the Peruvian Yine people, this article examines problems over orthodoxy in the context of Amazonian indigenous Christianities. It focuses on the grassroots-level inter-denominational relations between Catholic, Evangelical and Pentecostal Yine Christians and shows, how Yine prayer practices work as an important field for negotiating social relations and legitimate Christianity. The article argues that these negotiations are fundamentally tied to Amazonian socio-cosmological logics concerning corporeality, and that they can be profitably studied from the perspective of prayer ideology.