Some ministers would like us to believe that justification and salvation by grace through faith just suddenly appeared when the Son of God lived and died in the first century. They imply that God changed His approach to saving men—that He was either losing the battle to Satan, or the way He had given man was just too hard. It also implies that men under the Old Covenant were saved by keeping the law.
Once a person has sinned, he is under the penalty of the law, and his righteousness is not sufficient to justify him before God. Since all have sinned, the whole world is guilty before God. It takes a righteousness apart from lawkeeping to do this.
Then Paul says that this righteousness is revealed in the Old Testament Law and Prophets! The teaching has been there all along, all through the centuries from Moses to Christ and down to our time! God never changed His course. In the first century, He only openly revealed the means, Christ, through whom would come the righteousness that will justify one before God.
Men have always been justified and saved by grace through faith. People who were saved during Old Testament times looked forward in faith to this being accomplished. We look backward at it as a promise and as fulfilled prophecy.
John W. Ritenbaugh
Is God a False Minister?
This passage shows us the foundation of understanding justification by faith and thus where we stand in our relationship with God. Paul explains that, regardless of who one is and what he has done that might be considered as righteousness, God owes Him nothing but death because "all have sinned." Sinners are those under the law, and the law condemns them, making them subject to its power to take the sinner's life. Each person's own transgressions against the law and God place him in that position.
Sin is something each sinner is responsible for, and once the individual has sinned and earned the death penalty, the sin cannot be forgiven simply because he does good to make up for it. God did not make him sin. A clear example is Adam and Eve: God obviously did not make them sin; each of them chose to sin. Romans 3:20 clearly states that no sinner can justify himself through law-keeping. The law's purpose is to make known what sin is.
Once a person sins, everything is seemingly stacked against him. The sinner can in no way make up for what he has done. Therefore, since justification cannot be claimed as a right due to his keeping the law, if a person desires to be forgiven, the only alternative is that justification must be received as a gift.
John W. Ritenbaugh
Living By Faith and God's Grace (Part Two)