In this paper I present a model for describing the change in religion that took place during the Roman imperial period, a model that is built around a contrast between orthopraxy and orthodoxy. I begin with a brief survey of the most important earlier models of religious change in the Roman empire, followed by an initial sketch of my own proposed model. In the third and fourth sections I elaborate on this model in more detail by developing it through two brief case studies: the Graeco-Roman practice of animal sacrifice and the nascent Christian discourse around that practice. In analyzing animal sacrifice, I focus on its role in constructing the socio-political and cultural structures of the Roman empire. For the Christian discourse of sacrifice, I limit myself to one particular text, Paul’s first letter to the Corinthians, which provides some of the earliest surviving reflections on sacrifice by a Christ-follower. I close with a few comments on some of the limitations as well as the potential of my proposed model.