This article addresses the complex legal endeavour to shape the frontiers between two of the most fundamental liberal rights in multicultural nation states: the right to cultural difference and the right to religious freedom in Colombia. I follow one dispute, between members of the indigenous Arhuaco group who are Evangelical Christians and their indigenous local authorities. This example illuminates longstanding debates surrounding the relationship between religion and politics within legally plural states. I put together different scales of analysis for understanding: (i) the legal definition of the right to religious freedom and the right to ethnic cultural difference as private or public and individual or collective; (ii) the debate about the political meaning of religious practice by studying, for example, how it relates to claims over inequality and land access; and (iii) the importance of understanding the meaning of conversion for addressing the legal difficulty of creating a sustainable boundary between these two rights.