The doctrine of original sin was one of the most fiercely contested matters among the reformations of the sixteenth century on account of it being a dogma at the unsteady intersection of philological, soteriological, and sacramental debates in the earlier half of the century. The overlapping crux of these debates gravitated around this central question: What did Paul mean by the “sin” that “entered into the world through one man” in Romans 5:12? Erasmus offered the first major challenge to the doctrine of original sin in this period by questioning its exegetical grounding with his new translation of Romans 5:12 and by inadvertently appealing to Pelagius’s reading of the verse to argue that sin is transmitted exclusively through imitative acts of Adam’s transgression. Luther and Melanchthon, following in the line of the Augustinian-Lombardian sin tradition, argued through their readings of Romans 5-7 that original sin is properly defined as concupiscence but also insisted that this positive corruption and inclination to sin remains as sin even in the baptized. Zwingli, amid the Anabaptism controversy, argued that original sin should not be understood as sin per se but rather as an original sickness arising from Adam’s transgression. Fundamental to his argument was his reliance on Origen’s theology of sin, transmitted sickness, and the mors peccati as detailed in Origen’s commentary on Romans 5:12-14. This view was largely rejected, however, by the wider Reformed tradition, even as early Reformed figures such as Oecolampadius, Bucer, Bullinger, Calvin, Vermigli, and Beza had different ways of articulating the doctrine while still maintaining (like Luther and Melanchthon) the idea that original sin is truly sin. What is revealed in this exploration of more than 67 different commentaries on Romans, produced between 1512-1563, is that the sixteenth century was not simply the “Age of Paul,” but an age of rereading Paul in dialogue with his most influential interpreters in the Western tradition. These exegetical and theological disputes over original sin in the sixteenth century—considered through the long history of exegesis in the Western tradition—may best be understood as the violent re-collision of the Pelagian, Augustinian, and Origenian traditions of interpreting Paul’s Letter to the Romans.