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 3:20)
It is clear from this passage’s context that Paul the apostle is discussing the limitations and the effect of the Law of Moses. The limitation of any system of law is its inability to justify its violator. Simply put, keeping law will not save one who has violated that law. The law identifies him as a sinner. The Law of Moses served to teach Israel about their sin and its guilt, and pointed them toward the Christ who would save them “by grace, through faith” (Rom. 3:19, 23-26, 30; Eph. 2:8). We do not go to the Law of Moses for justification from sin, we go to Christ and His gospel. Thank God each day for the great mercy and salvation He gives you in Christ (Rom. 1:16-17; 5:1-2).