What is original sin?

Most people, left to their own reasoning, assume that sin is simply something a person does: a bad choice, an occasional lapse, a list of wrongs that could in theory be outweighed by enough right actions. Scripture teaches something more sobering and, in the end, more hopeful: sin is not only what we do but what we are, a condition inherited from our very first ancestor and present in every human being from birth. This is what theologians call original sin.

David expresses this with startling honesty in Psalm 51, written after his affair with Bathsheba. He does not merely confess the specific sins of adultery and murder; he traces the root deeper, confessing, behold, I was brought forth in iniquity, and in sin did my mother conceive me (Psalm 51:5). David is not accusing his mother of wrongdoing in conceiving him. He is confessing that sinfulness was present in him from the very beginning of his existence, not picked up later along the way.

Paul explains the mechanism in Romans 5: sin came into the world through one man, and death through sin, and so death spread to all men because all sinned (Romans 5:12). Adam was not merely the first sinner whose bad example the rest of us later chose to follow. As humanity's appointed representative, his sin was legally counted against the whole race he represented, and his corrupted nature was passed down to every one of his descendants.

This means original sin has two dimensions. There is inherited guilt, the legal condemnation that comes simply from being counted in Adam (Romans 5:18-19), and there is inherited corruption, the actual sinful nature every person is born with, which produces sinful desires and actions from childhood onward. Both dimensions are necessary to understand what Scripture means when it says we are, by nature, children of wrath, like the rest of mankind (Ephesians 2:3).

You do not need advanced theology to notice this doctrine confirmed. No parent has ever had to teach a toddler how to lie, grab, or throw a tantrum of selfish rage; those things emerge naturally, while patience, generosity, and honesty have to be painstakingly taught and modeled. Scripture's diagnosis matches what every honest observer of human nature, believer or not, eventually notices: none is righteous, no, not one (Romans 3:10).

This is not the same as saying every person is as evil as they could possibly be. Common grace restrains sin's full expression in society, and unbelievers are capable of real acts of kindness, love, and civic virtue. But even the best human deeds, apart from faith in Christ, are tainted at the root by self-interest and fall short of the perfect love and worship of God that his law requires (Isaiah 64:6).

Original sin can sound like bleak news, but understood rightly it is the necessary foundation for grasping how good the gospel truly is. If sin were merely a set of bad habits people could gradually improve through willpower or self-help, then Jesus's death on the cross would be an overreaction, and salvation could plausibly come through effort. But if sin is a condition running to the very root of who we are from birth, only a rescue from outside ourselves, a genuine new birth, can address it (John 3:3-6).

This is precisely what Christ offers. He did not come to help good people become slightly better; he came to give life to those who were dead in trespasses and sins (Ephesians 2:1). Original sin explains why every single human being, without exception, needs a Savior, and it magnifies the extraordinary grace of a God who provided one before we ever asked.

Some object that it seems unjust for later generations to inherit guilt from a sin they did not personally commit in the garden. Scripture answers this, as an earlier article on federal headship explains, by teaching that Adam did not act merely as a private individual but as the divinely appointed representative of the whole human race, so that his sin was truly, and justly, counted as belonging to everyone descended from him (Romans 5:18-19). This is the same principle of representation that later allows Christ's perfect obedience to be credited to everyone who trusts him.

It is worth remembering, too, that original sin is not the whole of the Bible's story about humanity. Every person still bears the image of God, however marred (Genesis 9:6), which is why human life retains real dignity and why unbelievers remain capable of real, if imperfect, goodness. Original sin explains our deep need for a Savior; it does not erase the worth God placed in every person he made.