This chapter deals with the question of whether it is possible to speak of the peccability of Jesus Christ in Theodore of Mopsuestia’s Christology. Theodore’s Christology is known for stressing the humanity of Jesus Christ to confront the logos-hegemonial tendencies in his day. In accordance with the testimonies of Scripture, Theodore nevertheless underlines the sinlessness of Christ. The chapter addresses the concept of sinlessness in Theodore’s Christology and poses the question of whether this sinlessness entails an inability to sin (impeccability). The answer to this question also provides thought-provoking impulses for the relation between Logos and Spirit Christology, as well as for a principal understanding of human nature.