19 Now we know that whatever the law says, it says to those who are under the law, that every mouth may be stopped, and all the world may become guilty before God. 20 Therefore by the deeds of the law no flesh will be justified in His sight, for by the law is the knowledge of sin. (Romans 3:19–20, NKJV)
Sin is the transgression of God’s law (1 Jno. 3:4). Those who are under law are accountable to it. Having observed the sins of Gentiles and Jews (Romans 1 and 2), and having documented them from the Scriptures (Rom. 3:9-18), the apostle has sustained his premise that all are guilty of sin and therefore, in need of salvation from sin’s bondage and death. Law is not the mechanism by which a sinner is justified (acquitted of guilt) – just the opposite. Law identifies the sinner and his sin. As Paul said, “by the law is a knowledge of sin” (v. 20). Attempting to be justified by keeping the law denies the nature of law and the presence of sin. The purpose of the law was not justification from sin. Its purpose was to magnify the reality of sin and man’s need for justification from it (Rom. 5:20; 7:7). Law does not justify sinners, it exposes the need for justification, which God offers through the gospel (Gal. 2:16; 3:1-2). The law reveals our sin. The gospel reveals our means of justification “through the redemption that is in Christ Jesus” (Rom. 1:16-17; 3:21-26). Thank God!