Few doctrines are more central to Christian discipleship than the doctrine of sin. We use the word frequently, sometimes casually, but sometimes our casualness betrays a misunderstanding of the depth of the biblical concept.
What Is Sin?
The standard definition is a good place to begin: Sin is missing the mark. God’s law is the standard—the mark—and sin is our failure to meet it. Augustine spoke of humans, by nature, being curved in on themselves. Sin is the orientation of the self towards the self, rather than towards the glory of God.
This is precisely what Paul means in Romans 3:23: “All have sinned and fall short of the glory of God.” To sin is to live a life, think a thought, or choose a behaviour that is in defiance of God’s glory. Sin, at its root, is not merely rule-breaking; it is a reorientation of the whole person away from God and towards the self.
Under Sin and Committing Sin
Romans 3:9 draws a distinction easy to overlook. Paul does not only speak of sins we commit, but of humanity being “under sin.” This is a statement about our condition (before conversion), not merely our conduct. As Lloyd-Jones put it, we are born in the realm of sin.
Two critical aspects of sin flow from this: the pollution of sin, and the guilt of sin.
The pollution of sin. Total depravity means that every part of our being is in rebellion against God. Sin does not merely affect what we do; it corrupts what we are. Every faculty—mind, will, emotions—is tainted by the fall.
The guilt of sin. Alongside pollution stands guilt—our legal standing before a holy God. This distinction is essential for understanding justification. Justification by faith alone does not address the pollution problem; it addresses the guilt problem. In Christ, the guilt of sin is removed: We are declared righteous before God by faith in Jesus Christ.
These two aspects require different remedies and unfold across different timeframes. Justification deals with guilt—decisively, at conversion. Sanctification addresses pollution—progressively, over a lifetime. And glorification finally eradicates the pollution altogether, so that the believer is saved completely from the power, pleasure, and presence of sin.
For the Christian, then, Romans 6 is critical: We are no longer “under sin” in the pre-conversion sense. We are no longer enslaved to the body of sin. Yet we live in the overlap between justification and glorification, and so a lifetime of dealing with sin’s polluting effects remains.
Three Kinds of Sin—and Why the Distinction Matters
All sin is sin. Every act of missing the mark falls short of God’s glorious standard. But the contributing factors behind sin vary, and recognising this variation matters enormously for pastoral care and personal sanctification. We might consider three broad categories.
The sin of weakness. Sometimes we sin not because we are defiant but because we are depleted. Consider a mother who has been up most of the night with sick children. By morning she is exhausted, weak in body, running on three hours’ sleep. She is far more vulnerable to the temptation of impatience—to saying things she would not say if she were well rested. Her impatience is still sin. She is still responsible. But there is a weakness of the body that has set the conditions for the failure. Accountability and compassion must go together here.
The sin of folly. Sometimes people sin without fully realising that what they are doing is sinful. This is not an excuse, but it is an explanation—and it shapes how we respond. This person is ignorant, not in a pejorative sense, but in the straightforward sense: He or she has not been instructed and therefore has not known what God’s word requires. Paul reflects something of this when he writes to the Ephesians: “Let the thief no longer steal, but rather let him labour, doing honest work with his own hands, so that he may have something to share with anyone in need” (Ephesians 4:28). The implication is that some in Ephesus had not grasped that stealing was wrong. Paul simply lays it out and corrects the behaviour. Even Jesus’ cry from the cross gestures at this category: “Father, forgive them, for they know not what they do” (Luke 23:34). Ignorance does not cancel guilt, but it does shape the response.
The sin of defiance. The Old Testament speaks of “high-handed” sins (see Numbers 15:30)—deliberate, premeditated acts of defiance against God’s law. Certain sins fell into this category in Israel: murder and blasphemy among them. Significantly, there was no sacrificial provision for high-handed sin under the Mosaic law. The penalty was death. The severity of the response reflects the gravity of wilful, knowing rebellion. I am reluctant to apply this category of sin to Christians. The Old Testament background clarifies what is at stake when sin is not a matter of weakness or ignorance, but of deliberate choice.
Pastoral Discernment in Practice
Paul’s instruction to the Thessalonians maps these categories onto congregational life with pastoral precision. Writing in 1 Thessalonians 5:14, he urges the church: “Admonish the idle, encourage the fainthearted, help the weak, be patient with them all.” Three groups, three responses. The idle—those who know better and are in wilful neglect—must be warned. The fainthearted—the easily discouraged, those prone to despair—should be encouraged. The weak—those struggling under the burden of bodily frailty or limited understanding—can be helped.
The practical implication is that effective pastoral care and meaningful accountability require discernment. When someone is caught in sin, the question is not only, “What did they do?” but also, “Why did they do it, and what does this person need?” Consider someone struggling with pornography. Did he or she stumble once, came to you broken and repentant, and ask for help guarding against a repeat? Or is this someone who grew up in a home saturated with sexual sin and who is deeply entangled? Or is it a long-term lifestyle that preceded conversion, and which now requires sustained, intensive work? The sin in each case is real and must be addressed, but the pastoral approach will differ in tone, intensity, and focus.
This discernment also calls for self-knowledge. Part of helping people grow in holiness is helping them understand their own patterns: what triggers their particular sins, what situations or states make them vulnerable, what disciplines and guards they need to put in place. Sin may be all the same in its essence—falling short of God’s glory—but the path out of it requires knowing both the sin and the sinner.
Conclusion
The doctrine of sin is not merely a theoretical matter. It shapes how we understand ourselves before God, how we receive the gospel, and how we live together in the church. To understand that we are born under sin—not merely prone to sins—is to grasp the depth of our need for a Saviour. To understand that Christ deals with the guilt of sin, while the Spirit works progressively at its pollution, is to hold together justification and sanctification without collapsing one into the other. And to understand that sin comes in different forms—weakness, folly, and defiance—is to become more patient, more perceptive, and more genuinely helpful to those around us who are fighting the same battles we are.