Across the world and throughout history, people have negotiated religious and social change by marshalling the mythological resources at their disposal. In cases of conversion to Christianity, this dynamic has often taken the form of constructing an isomorphism between traditional mythical narratives and those learned from the Bible, a manifestation of the process I here call 'mythic conflation'. In this article I explore how the Oksapmin of the West Sepik Province, Papua New Guinea, have conflated aspects of Bible stories with two of their traditional narratives in an attempt to overcome cosmological contradiction. From the etic perspective, this has partially collapsed difference in the construction of syncretic religious forms. From the emic perspective, by constructing for themselves an ancestral precedent of this kind, the Oksapmin support a claim of having revealed the mystery of Christianity's local origin.