What is original sin?

Original sin is the doctrine that the sin of Adam in the Garden of Eden did not affect only Adam — it affected every human being who would ever live. We do not simply inherit a tendency toward sin; we inherit guilt, corruption, and spiritual death.

Romans 5:12 is the foundational text: "Therefore, just as sin came into the world through one man, and death through sin, and so death spread to all men because all sinned." The connection between Adam's sin and universal human death and guilt is explicit. Paul's argument in Romans 5:12-21 runs the parallel between Adam and Christ: just as condemnation came to all through one man's trespass, justification comes to all through one man's righteousness. The structure of both realities — the fall and the redemption — depends on the concept of representation: Adam acted as the head and representative of the human race.

Psalm 51:5 expresses the same reality from the inside: "Behold, I was brought forth in iniquity, and in sin did my mother conceive me." David is not blaming his mother. He is acknowledging that his sinfulness goes all the way down — it is not merely a collection of bad choices but the condition from which those choices flow.

What does original sin mean practically? It means that every human being is born in a state of spiritual death and moral corruption — not merely in need of improvement, but in need of resurrection. This is why the new birth is not optional for anyone, regardless of how moral or religious they appear. "Flesh gives birth to flesh, but the Spirit gives birth to spirit." (John 3:6).

Original sin is also the doctrine that makes the gospel make sense. If human beings are basically good and just need encouragement, the cross is absurd overkill. If human beings are dead in sin and under condemnation, the cross is exactly what was needed — and grace is not a supplement to human effort but its only alternative.