Reconsidering Original Sin and the Nature of Humanity
Question: In my history, when I have heard people talking about sin, they would divide it into two parts, original sin and actual sin. Original sin happened in the garden and changed the nature of Adam. Original sin is inherited, so all of us have a sin nature and thereby commit actual sin. Recently, I've heard people dividing it into three parts: original sin, inherited sin, and actual sin. What are the pros and cons of the two-part versus the three-part division?
The traditional two-part distinction between "original sin" and "actual sin" is widespread in conservative theology. In that scheme, "original sin" usually refers not simply to Adam’s initial act of disobedience, but to a supposed alteration of human nature that occurred as a result of that act. This altered nature, transmitted to all Adam’s descendants, is then viewed as the root from which "actual sins"—the concrete acts we commit—proceed.
More recently, some have attempted to refine this by speaking of three categories: original sin (Adam’s first sin), inherited sin (the sin nature or corruption passed on), and actual sin (our personal acts). While this adds terminological precision, it still rests on the same foundational assumption: that Adam’s fall changed the intrinsic nature of humanity and that this changed nature is passed down.
A close, literal reading of Scripture, however, does not clearly establish a change of human nature. What is explicitly described is a change of position and condition: Adam and Eve are expelled from the garden, barred from the tree of life, and thus barred from the environment in which death was absent. Humanity is now outside that protected context, subject to death and curse, but still in the image of God. Scripture continues, after the fall, to affirm humanity as made in God's image rather than in some new, essentially corrupted image.
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It is evident that from the beginning humans had genuine free will. Adam and Eve, before any fall or inherited corruption, chose to disobey. That reality alone shows that an inclination to test boundaries or to desire what is forbidden does not require a postulated "sin nature" fundamentally different from Adam’s original humanity. It may instead reflect the capacities of human nature as created, including the ability to choose wrongly.
The notion of a formally altered nature, transmitted to all, was systematized in large measure by Augustine and became embedded in both Roman Catholic and Reformed traditions. Once that doctrinal construct is accepted, it generates the need for further constructs to deal with its implications. For example, infant baptism in Roman Catholicism is tightly bound to the idea of removing original sin; various predestinarian or sacramental systems are developed to address the fact that, if all are born with a totally corrupted nature, some means must effectually overcome that condition.
If one does not begin with the Augustinian premise of a changed, inherited nature, the biblical problem appears differently. Humanity is seen as descended from Adam, outside Eden, mortal, separated from access to the tree of life, and living in a world under curse. The issue is not that humans are now a different kind of creature than Adam was, but that they are in a different place and relation—alienated from God's immediate presence and from life. The solution promised and provided is a rescuer from outside our condition who brings life and reconciliation.
On that reading, the common two-part distinction (original vs. actual sin) and its three-part variant (original, inherited, actual) are different ways of packaging a system that overstates what Scripture says about a change in human nature. The practical difference between the two schemes is mostly homiletical and didactic: three points preach more smoothly than two, but both assume the same underlying theory.
If one nonetheless wishes to describe the biblical situation in terms of categories, it is safer to speak in terms of Adam’s historical act of sin, the consequent entrance of death and curse into the human experience Romans 5:12, and the ongoing personal sins that each person freely commits. But to go beyond that and assert an ontological alteration of human nature in Adam, inherited in such a way that it functionally compels actual sin, is not clearly taught in the text and imports later theological constructions into Scripture.
Thus, the "pros" of the two- or three-part systems lie mostly in their internal coherence once one grants the Augustinian premises. The "cons" are that they risk reifying a speculative nature-change, foster additional theological complexities (such as the necessity of infant baptism or intricate predestinarian schemes), and can obscure the simpler biblical portrayal: humanity, still human and still bearing God's image, is nevertheless mortal and alienated due to Adam's sin and needs rescue, which God provides in Christ.
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