Genesis 1:26–28 famously affirms the creation of humankind “in the image of God” (imago Dei). Alright, but to borrow a famous phrase from Martin Luther’s Small Catechism—“What does that mean?”

Today this text is often read cosmologically. The creation of the heavens and the earth amounts to the building of a “cosmic temple.” The creation’s good order parallels the structure of the Temple of ancient Israel. Within this cosmic temple, human beings were endowed with special gifts so they could serve as “priests of creation.” They were icons of God whose task was to represent and co-respond to the Creator while tending to the flourishing of the good creation.

In medieval western theology, readers of Genesis typically understood the image of God within what has been called a “faculty psychology,” an account of the human soul that identified it with capacities. The capacity of the human soul to reason, for example, is grounded in intellectual power, the capacity to make choices in the power of will, and the capacities of perception and movement in the sensitive powers. These discrete capacities are infused by God into the “essence of the soul,” and they equip humankind to carry out the task of re-presenting the Creator to His creation. This is the imago Dei.

Of course, Martin Luther knew the Genesis text well. He extolled the co-regency of Adam and Eve before the fall. He also knew and worked with faculty psychology, often without objection. At the same time, he wanted to return theology to its biblical roots. Thus, his work as professor of theology in Wittenberg was focused upon the biblical text itself rather than the standard handbooks of theology. Early on he lectured on the Psalms and Romans. And for the last decade of his career, he turned to Genesis.

In his Romans lectures, Luther was deeply concerned with grace and human freedom. These concerns raised hard questions about human nature, both as originally created by God and as now vitiated by sin. Can a sinner turn to God and be reconciled by simply exercising his or her natural powers (reason and will)? Some of Luther’s teachers said yes. They insisted that the fallen sinner could love God and turn to Him even without the assistance of grace. “Do what is in you,” it was said, “and God will not deny you grace.” The sinner, on this account, takes the initiative. To that extent, getting right with God—”justification”—is a human work. The supposition behind all this is that the powers of the soul, and with that the image of God, remain intact within us even in our fallen state.

After a struggle with these issues as a young monk, Luther concluded that those teachers were wrong. Here his thinking connected with a crucial problem he faced when lecturing on Romans in the years 1515-16. What does Paul mean by the contrast between flesh and spirit (Romans 8)? Luther’s solution to this classical question was to read the difference not in a “Platonic” way, as a conflict between body and soul, but instead holistically, as two opposed realities pitted against one another within the whole human person. Flesh denotes the whole person under sin, spirit the whole person under grace. Thinking holistically, if sin is in a person, then it is in the whole person (Romans 7:17).

Luther’s holistic reading of fallen human nature seemed to call into question the image of God. He could even say that humankind was no longer the image of God and had become its opposite: the imago diaboli. This notion sparked controversy after Luther’s death. His Croatian disciple, Matthias Flacius, argued that sin is the “formal substance” of the fallen person. The Lutheran confessions rejected that position because it makes the human soul evil per se. Because God is the soul’s maker, Flacius cannot be right.

In his Genesis lectures, Luther, too, avoided Flacius’s error. Sin, he said, is a leprosy, a wound, or a corruption. It is not, therefore, “what we are.” Much good remains in the sinner, including the traditional powers of the soul. Still, Luther insists that all these powers have been touched by sin. Sin disables us from experiencing the fullness of joy proper to genuine heartfelt love for God. This is how Luther understands the traditional notion that original sin brought about the loss of “original righteousness.” Considering the imago dei holistically, therefore, Luther finds it not only lost but almost unimaginable. For its full restoration, we must await in faith and hope until that good last day.