This article focuses on the exegetical interpretation of Luke's narrative of the census (or registration) carried out at the time of Jesus's birth (Luke 2: 1–5). After some brief remarks on the juridical institution of the census (the so-called professio census) in ancient Rome, a selection of the exegetical interpretations of this pericope developed by various ancient and medieval authors is presented. Origen, Ambrose, Orosius, Bede and Bonaventure are discussed, among others. A number of medieval authors, including Dante Alighieri and Bartolus of Saxoferrato, are also considered. The analysis argues, on the one hand, that a spiritualization of the institution of the census occurred and led to the spiritual empire of Christ being seen as replacing the temporal empire of Augustus; on the other, that reference to this institution was used to legitimize political authority in the eyes of believers. This interpretative tradition is thus shown to offer a vivid example of the close intertwining of theological and juridical concepts and practices which has characterized the relationship between the Church and empire from the former's very beginning.