On the basis of a historical reconstruction of the stages through which the Christian notion of sin took shape in Protestantism, the significance of this term for modern bioethics is derived from its opposition to a holiness of God and his creatures, which in turn translates into the secular moral concept of dignity. This dignity imposes obligations to respect and to relationships that are sustained by faithfulness and trust. In being based on the gratuitousness of God's grace, such relationships preclude attempts at instrumentalization, denial of singularity, and subjection to market forces. Accordingly, reproductive cloning as well as exposing medicine to economical considerations can be classified as sinful. The difference between sinful acts and humans' sinful state furthermore permits to address the problems of evil and misfortune in the world, and to acknowledge humans' responsibility for the threats to humanity entailed by those ills. While the Christian faith relies on God's mercy, it also imposes the task of following Christ by fighting against evil and misfortune.