What is sin?
Question 6001
It is one of the most fundamental questions we can ask, and yet so many struggle to define it clearly. What exactly is sin? The world around us has largely abandoned the concept, preferring words like “mistake” or “poor choice” or even dismissing moral failure altogether as merely the product of environment or psychology. But Scripture speaks with unmistakable clarity on this matter, and if we are to understand the Gospel itself, we must first understand what it is that separates us from a holy God.
The Biblical Definition
The clearest definition of sin in all of Scripture comes from the apostle John: “Everyone who makes a practice of sinning also practices lawlessness; sin is lawlessness” (1 John 3:4). The Greek word used here is ἁμαρτία (hamartia), which carries the idea of missing the mark. Picture an archer drawing back his bow, releasing the arrow, and watching it fall short of or veer away from the target. That is the essence of sin. God has set a standard, His own perfect character expressed in His law, and sin is any failure to meet that standard.
But we must be careful not to reduce sin merely to breaking rules. Sin is fundamentally relational. When David committed adultery with Bathsheba and arranged for her husband Uriah to be killed, his confession in Psalm 51 is striking: “Against you, you only, have I sinned and done what is evil in your sight” (Psalm 51:4). Yes, David had wronged Bathsheba, wronged Uriah, wronged the nation. But at its deepest level, his sin was against God Himself. Every sin, whether against another person or seemingly private, is ultimately an offence against the One who made us and to whom we owe everything.
Sin as Falling Short
Paul puts it plainly in Romans 3:23: “For all have sinned and fall short of the glory of God.” The verb “fall short” is in the present tense in the Greek, ὑστεροῦνται (hysterountai), suggesting an ongoing condition. We do not merely commit individual acts of sin; we exist in a state of falling short. God’s glory, His perfect moral excellence, is the standard, and none of us measures up. Not once. Not ever. Not on our best day.
This is why the Gospel is such good news. If sin were merely about behaviour modification, we might hope to fix ourselves. But sin runs deeper than what we do; it touches who we are. We need more than self-improvement. We need a Saviour.
Sin as Active Rebellion
Scripture also presents sin as wilful rebellion against God’s authority. Isaiah 53:6 describes it this way: “All we like sheep have gone astray; we have turned, every one, to his own way.” There is something deliberate here. We have not merely wandered accidentally; we have turned. We have chosen our own path over God’s. This is the heart of sin: declaring independence from God, setting ourselves up as the arbiters of right and wrong, deciding that we know better than our Creator.
This was the essence of the original temptation in the Garden. The serpent promised Eve, “You will be like God, knowing good and evil” (Genesis 3:5). The appeal was not merely to appetite but to autonomy. “You can be your own god. You can determine for yourself what is right and wrong.” And humanity has been living out that lie ever since.
Why This Matters
Understanding sin properly is essential for understanding grace. If we minimise sin, we will inevitably minimise the cross. If sin is just a minor problem, then Jesus’ death was an overreaction. But if sin is what Scripture says it is, a catastrophic rebellion against the infinite God that has infected every part of our being and separated us eternally from our Creator, then the cross begins to make sense. It took nothing less than the death of God’s own Son to deal with the problem we had created.
So when someone asks, “What is sin?” we can answer: Sin is any failure to conform to the moral law of God in act, attitude, or nature. It is missing the mark of His perfect standard. It is falling short of His glory. It is rebellion against His rightful authority. And it is the reason we so desperately need Jesus.
“Everyone who makes a practice of sinning also practices lawlessness; sin is lawlessness.” 1 John 3:4
