We know that our old human was crucified with him so that the body of sin might be destroyed, and we might no longer be enslaved to sin.
That is not the way you learned Christ! For surely you have heard about him and were taught in him, as truth is in Jesus. You were taught to put away your former way of life, the old human, corrupt and deluded by its lusts, and to be renewed in the spirit of your minds and to clothe yourselves with the new human, created according to the likeness of God in true righteousness and holiness.
Do not lie to one another, seeing that you have stripped off the old human with its practice and have clothed yourselves with the new [human], which is being renewed in knowledge according to the image of its creator.
Within the Augustinian tradition in Western Christianity, there has been a basic explanation for human evil: that a sinful nature is inherited from our ancestors, going back to the Fall of Adam. This explanation then sets up for the solution to sin in Jesus Christ as the one by whose grace we are forgiven and set free from our sinful nature to live life righteously. The basic contours of this theological anthropology have had a tremendous intellectual and social influence on the Western world.
However, there is a weak point with this anthropological narrative. Insofar as it relies upon the comparison and contrast of Adam and Jesus in Romans 5, there is little direct textual support for the genetic inheritance of sin from one’s parents. If true, it would be a sufficient explanation for what Paul says, but the Western doctrine of original sin is by no means unanimous within the whole Christian tradition. It is the rejection of this doctrine that partly defines the differences between Eastern Orthodoxy and Western Catholicism. Instead, Eastern Orthodoxy appeals to the ancestral sin of Adam that leads to the inheritance of the environment created as a consequence of the sin, while attributing sin ultimately to the devil. To that end, the interpretation of the fall of Adam is not much unlike the debates in science between the role of genetics and environment in various biological and physiological traits and diseases.
On the one hand, it isn’t out of bounds to consider that sin was inherited from parents. After all, many of the traits and characteristics of a parent are observed to be passed down to their children. Furthermore, David in the penitential Psalm 51 cries out “Indeed, I was born guilty, a sinner when my mother conceived me.” Nevertheless, it is not entirely clear this is meant literally as an explanation for the sin of all people, but rather as a hyperbolic device to establish how deep sin is a part of David’s own life. In a similar expression in Psalm 58.3, David ascribes people’s wickedness to coming from the womb by their speaking lies from their birth. The hyperbolic nature of David’s speech may be a way of figuratively pointing to familial lineage as the origin of a person’s specific sins, but it is not necessarily intended as an explanation with a universal scope for all sin.
If we look more closely at Paul’s discourse in Romans 5.12-21, it doesn’t seem that Paul says anything dramatically new that couldn’t have already been inferred from the creation narrative. No new information is being given about the role of Adam in the problem of sin. Rather than trying to provide specific teaching about Adam and sin, by comparing Romans 5.12 with Wisdom of Solomon 2.24, it seems that Paul’s purpose is more geared to rebutting the idea that the devil is the cause of sin. Instead of sin being the problem for those who belong to the devil, sin is a universal reality due to Adam’s actions. Paul cannot effectively make this argument to an audience who believes the devil as the cause by trying to add new ideas and information that would not be readily inferred from Israel’s Scriptures. Instead, Paul is summarizing what the Scriptures do say, which makes no mention of the hereditary nature of sin but instead points towards the condemnation that God pronounced in response to Adam and Eve’s transgression. In effect, God’s judgment against the couple separated humanity from God’s close, intimate presence, separated them from the provision of the tree of life, and brought pain and strike with human relations with each other and the world around them. Unless one tries to infer doctrines about sin and death that are neither expressly stated nor narratively represented in Genesis 3, the Fall narrative fits more so within the environmental explanation: sin is the consequence of living in a world that the actions of Adam and Eve brought to fruition.
I would go so far as to suggest that Paul’s understanding of the nature of redemption in Jesus Christ necessarily pulls from this environmental explanation. For Paul, he imagines believers putting on a new humanity by our union with Christ that is in according to the image and likeness of God back in Genesis 1. Jesus Christ as the image of God is the restoration of the Genesis 1 narrative for believers over and against the Genesis 3 narrative. This doesn’t make cohere well if sin is inherited as the body that we inherited from our parents still exists even as we believe in Christ: how can there be a crucifixion of the old human and the destruction of the body of sin if sin is a byproduct of our the body we received at birth? If, however, the body is formed by living in the world to become what Paul comes to refer to as the flesh, then Paul’s understanding of the redemption in Christ makes more sense. One can put on the new humanity because the old humanity was something learned as part of one’s former way of life, but one learns a new way in Christ which leads to the emergence of a new humanity. There is no intrinsic, genetic sinful nature that must be abolished, but there is only a body that the powers of sin and death have colonized and enslaved, which Paul refers to as the flesh, that is resisted, fought against, and successfully conquered through union with the crucified and resurrected Christ so that God’s grace comes to exercise dominion.
For Paul, there is nothing no less radical than the emergence of a new human, a new human nature that is unlike the old. This is not simply just a metaphor for having a different way of life with a few new habits, but there is a stark qualitative difference between what motivates and directs human behavior and life. The desires of the Spirit, rather than the out of control desires of the flesh, define the life of believers. In Christ, believers are having a new humanity that is formed according to the original creation intentions where God has drawn near to the believer to lead to living in the direct presence of God in the New Jerusalem, where the provision of life given in Christ that will culminate in the resurrection, where the changes of relations between each other in Christ and the ultimate restoration of right relations of everything in heaven and earth in the eschaton. The new humanity is a presently in-breaking reality in believer’s lives through the Spirit, who is given as a down-payment for the culmination of what is to come in the eschaton. In Paul’s minds, there is nothing less than an entirely different anthropological destiny that defines believers in Christ. This would stand in stark contrast to the Roman notion of the novus homo (“new man”) who were the first of their family to serve the Roman Senate, as the new humanity are given to the service of the Lord Jesus Christ rather than the centers of Roman power.
Paul’s explanation doesn’t fit well with either the Western emphasis on the hereditary nature of sin and guilt, nor with the Eastern emphasis on describing the origin of sin to the devil. For Paul, sin in the world originates with Adam, not the devil, but it is transmitted not through procreation but through the judgment pronounced by God that pushed humanity from God’s presence, isolated them from the provision of life, and overturned the harmony of creation (if one reads Genesis 3.22-24, the alternative to doing so would have been a far worse possibility) that has been bequeathed to humanity. For Paul, the solution, the cure is something so dramatic as to suggest that those in Christ take on a fundamentally different human nature from the world they inhabit, not in terms of materiality or physicality, but in terms of differing motivations brought about by the Spirit that is grounded upon faith in God and hope in the future that longs to be joined together in love.