Taken from Concise Reformed Dogmatics (1992).
“3. It remains to discuss whether we should consider the law as the preeminent means whereby knowledge of sin is worked in man. We encounter this idea in Pietism and a number of representatives of the Second Reformation.
In opposition to this view we identify two clear perspectives. In the first place we recall the fact that Paul declared the law to be “weak through the flesh” (Rom. 8:3). We realize that he uses these words in a different context than we do here. Yet there is a similarity. The undoing through the law is part of true repentance. It may be viewed as the dying of the old nature. If the law on its own (preceeding and therefore separate from the gospel) would be able to break a man, it would be an effort on the part of the law. However, the law is unable to change a sinful heart. Works of the law do not please God. It is rather sinful man tends to employ the law to justify himself. It is impossible for the law by itself to humble man before God.
The law rather leads to hardening of sin. Paul clearly identifies this tendency of the law to multiply sin (Rom. 3:20; 5:20). He recognizes God’s judgment in this. Sinful man employs the law to justify himself before God. This is how he multiplies his sins. He abuses the law to this effect.
One should not treat the preaching of the law in isolation. The entire Word of God comprises both the law and the Gospel. No one can preach the Gospel while ignoring the accusation of the law. Theologically, the accusation comes first. How can the acquittal be announced before the accusation has been brought foward?
As accusation, the law always precedes the preaching of the gospel and resonates in it. However, by limiting oneself to the accusation, one would fall short of the mandate to preach God’s Word. By stopping after the word of the law, one cuts the gospel in half by eliminating its saving and purifying perspective. It causes despair without indicating the way back to God” (433, bold mine).