The Flacian controversy in mid-16th century Lutheranism turned on the question whether as a consequence of original sin the image of God in humankind has been lost and replaced by the image of the devil. Is the fallen human being evil per se? Examining Martin Luther’s comments on the story of creation and fall in his Genesis Lectures (1535-1545), I argue that Luther’s insistence on the loss of the imago dei results in an anthropology closer to that of Thomas Aquinas than to Luther’s uncompromising disciple, Matthias Flacius Illyricus. For both Thomas and Luther, original sin is a holistic term that reflects the absence of original righteousness in the essence of the soul. Luther rejects any substantial reading of original sin that would ontologize it as the very substance of the human being. His anthropological holism means that sin has a deleterious effect on the whole human being, including all the powers of body and soul. Sin is privative, a spiritual leprosy that corrupts the whole human being.