The fifth petition of the Lord’s Prayer teaches us to pray, “Forgive us our debts, as we also have forgiven our debtors” (Matt. 6:12). It brings us to the core problem of the human condition—sin. What is sin? Why does it require God’s forgiveness? A look at Adam and Eve’s original sin (Gen. 3:1–24) answers both questions.

According to Genesis 1–2, God created Adam and Eve in his “image, “blessed them,” made them stewards over animals, and pronounced their existence “very good” (1:26–31). Unlike us, they lived in such simplicity and innocence that they were “both naked” but “felt no shame” (2:25). God provided food for them, placing them in a garden with a simple request to “work it and take care of it” (2:15). He gave them one prohibition: “you must not eat from the tree of the knowledge of good and evil, for when you eat of it you will surely die” (2:17).

Genesis 3 opens ominously. A crafty snake approaches Adam and Eve and questions God’s commandment: “Did God really say, ‘You must not eat from any tree in the garden?’” (3:1). When they answer affirmatively, the snake denies the commandment’s truthfulness and questions God’s motivation for giving it in the first place: “You will not surely die,” he says. “For God knows that when you eat of it your eyes will be opened, and you will be like God, knowing good and evil” (3:4–5).

Instead of rebuking the snake and obeying God, Adam and Eve “took some [of the fruit] and ate it” (3:6). Their action reveals the nature of sin. As the Westminster Larger Catechism defines it, “sin is any want of conformity unto, or transgression of any law of God, given as a rule to the reasonable creature” (Question 24). By failing to rebuke the snake, over whom they had dominion, Adam and Eve sinned by omission. By eating the forbidden fruit, they sinned by commission. Not doing what God commands is as sinful as doing what God prohibits. Adam and Eve sinned both ways.

The first consequence of Adam and Eve’s sin was shame over their loss of innocence (3:7). Fear of God’s judgment quickly followed (3:10). Then, when God confronted them, they fell to blame-shifting (3:12–13). From this followed a rupture in peaceful relationships between humans and the rest of creation (3:15, 17–19), among humans themselves (3:16), and between humanity and God (3:23). Finally, as the prohibition had warned, separation from God and death were imposed as a judgment on humanity (3:19, 22–24).

These last two consequences especially explain why sin requires God’s forgiveness. When we alienate ourselves from God through disobedience, only he can choose whether to welcome us back into his presence. And when we experience the judgment of death, only God can bring us back to life.