Through its threats of punishment, the law of God restrains sin. Whether we encounter the moral law written in the Old Testament or have access to it only as it is inscribed on our consciences (Rom. 2:14–15), we find our outward behavior held in check. Human beings do not fulfill all of their sinful desires out of fear of the law’s judgments, and thus civil society is, in the main, preserved.
Yet though the law restrains the outward expression of sin, the fact that we do not give full expression to our depravity does not make us righteous. For while the law restrains our actions, it also inflames the wicked desires of our hearts, increasing our transgression. Outwardly, we might appear to be good people, but inwardly, the encounter of the fallen human heart with God’s law always, apart from grace, increases our desire to reject and break this law. The law reveals to us that sin is not merely an external matter but an inner reality, helping us see that we are far more depraved than we would like to imagine.
Paul makes this point in today’s passage, explaining how the law’s commandment against coveting ends up making fallen people more sinfully desirous of those things that are not properly theirs (Rom. 7:7–8). In fact, in one sense, all sin originates in covetousness. We covet the control that God has, so we create idols that we can manipulate. We commit adultery because we covet another person’s spouse and seek to take that spouse for ourselves. In sum, the moral law reveals and exacerbates our wicked, covetous desires.
In describing how the law reveals and excites sin, Paul does not mean that we are wholly unaware of covetousness before we encounter the law or that we are without sin apart from the law (vv. 9–13). After all, he has already made it quite clear in Romans 5:12–21 that we are born in sin and inclined to sin before we have any conscious awareness of the moral law. Dr. R.C. Sproul explains that in this portion of Romans 7, Paul refers to “someone spiritually dead to any awareness of the gravity of sin.” The law does not so much give sinners a definition of sin as it shows sinners that their sin is far deeper than they first thought. Until we come face-to-face with the moral law, we spend most of our lives ignoring the sin that we know is there or telling ourselves that we are better than we actually are. John Calvin comments, “Without the law we are either too dull of apprehension to discern our depravity, or that we are made wholly insensible through self-flattery, according to what follows.”