"Therefore, as sin entered into the world through one man, and death through sin; and so death passed to all men, because all sinned."
— Romans 5:12
Quick Answer
Sin entered the world through Adam's disobedience in the Garden of Eden, when he and Eve chose to distrust God's word and eat from the one tree he had forbidden (Genesis 3:6, Romans 5:12). Their rebellion plunged the entire human race into a fallen condition, bringing death, corruption, and separation from God into what had been a perfect creation.
From a Perfect World to a Broken One
It is easy to forget, amid so much brokenness, that the world was not always this way. Genesis describes a creation God repeatedly called good, culminating in a world he called very good after making humanity in his own image (Genesis 1:31). There was no death, no disease, no shame, no fractured relationship between God and the people he had made. Adam and Eve walked with God in the garden without hiding, without fear, without guilt.
So how did we get from that world to this one, filled with suffering, cruelty, and decay? The Bible answers this question directly and historically in Genesis 3, and the rest of Scripture treats that account not as myth but as the actual hinge point of human history, the moment everything changed.
The Temptation in the Garden
God had given Adam one restriction among great abundance: he could eat freely from every tree in the garden except one, the tree of the knowledge of good and evil, with a clear warning that eating from it would bring death (Genesis 2:16-17). Into this good arrangement came the serpent, described as more crafty than any other creature God had made, who twisted God's word into a question: “Has God really said, 'You shall not eat of any tree of the garden?'” (Genesis 3:1).
The serpent then flatly contradicted God, promising that Eve would not die but would instead become like God, knowing good and evil (Genesis 3:4-5). The temptation targeted the one thing every relationship is built on: trust. Would Eve, and then Adam, believe God's word about what was good for them, or believe the serpent's version instead?
The Choice That Changed Everything
Eve saw that the tree was good for food, pleasing to the eye, and desirable for gaining wisdom, and she took its fruit and ate it, giving some also to her husband, who was with her, and he ate (Genesis 3:6). Notice that Adam was present and complicit, not an innocent bystander deceived from a distance. Paul later places the primary responsibility on Adam specifically, since he was the covenant head representing the whole human race (Romans 5:12, 1 Corinthians 15:22).
The immediate result was not the wisdom the serpent promised but shame, fear, and hiding. Their eyes were opened, and they realized they were naked, so they sewed fig leaves together and hid from the presence of God among the trees of the garden (Genesis 3:7-8). Innocence was gone, replaced by guilt they had never known before.
Consequences That Reached Every Corner of Creation
God's judgment on that first sin was severe and far-reaching. The serpent was cursed, the woman would experience pain in childbirth and relational conflict, the man would labor against a resistant ground, and both would eventually return to dust (Genesis 3:14-19). Death entered a world that had never known it. More than that, Adam and Eve were driven out of Eden, cut off from the tree of life and from the unbroken fellowship they had enjoyed with God (Genesis 3:22-24).
This was never a private, isolated event. Paul explains that through one man sin entered the world, and death through sin, and so death spread to everyone, because everyone sinned in and through Adam's representative act (Romans 5:12). Even creation itself was subjected to futility and now groans, waiting for redemption (Romans 8:20-22).
The First Promise of Rescue
Remarkably, even in the middle of pronouncing judgment, God spoke the first promise of the gospel. He told the serpent that the offspring of the woman would one day crush his head, though the serpent would strike his heel (Genesis 3:15). Theologians call this the protoevangelium, the first announcement of the gospel, pointing forward to a coming deliverer who would undo what Adam had done.
Even the immediate aftermath of the fall carries hints of grace alongside judgment. God clothed Adam and Eve with garments of skin rather than leaving them in their inadequate fig leaves (Genesis 3:21), a small but significant act showing that even as he judged their sin, he was already covering their shame, foreshadowing the greater covering his Son would one day provide.
That deliverer is Jesus Christ. Where Adam's disobedience brought condemnation and death to all, Christ's obedience brings justification and life to everyone who believes (Romans 5:18-19). The story of how sin entered the world is tragic, but it is not the end of the story. It is the setup for the greatest rescue in history.