This paper examines the diabolisation of Oksapmin tamam (here glossed as ‘witchcraft’) as an example of negative cosmological integration. The article takes as its point of departure Robbins’s model of cultural syncretism developed in a series of recent papers, wherein diabolisation occurs as people insert those aspects of their indigenous religion that do not contravene the Christian God’s paramount creative power into the Christian cosmos as representatives of the Devil. Through my own discussion of the diabolisation of Oksapmin witchcraft, I build upon the model in three main ways. First, I draw attention to the role of the mission in providing and enforcing these negative moral terms of reference. Second, the article highlights that in cases of negative cosmological integration, whether within or outside the frame of Pentecostalist Christianity, syncretic melding and mixing may occur, regardless of rhetoric to the contrary. Finally, I point out that the subordination of indigenous religious realities within the Christian cosmos does not necessarily entail their restriction or reduction of expression, as Robbins shows for the Urapmin nature spirits known as motobil. Indeed, in the case of witchcraft, integration into the Christian cosmos and related complexes of deliverance may actually serve to intensify and amplify their expression.