Romans 5:20-21 Now the law came in to increase the trespass, but where sin increased, grace abounded all the more, so that, as sin reigned in death, grace also might reign through righteousness leading to eternal life through Jesus Christ our Lord.
Here the apostle refers to the Mosaic Law, appearing to address his kinsmen of the flesh once again. It is not the design of the Law to create sin, what Paul is saying here is that the Law provokes sinners to sin. It’s the same effect as one of us seeing the “wet paint” sign – we want to test that. It’s what happens when we face a speed limit that is simply too low for the road and conditions – we want to go faster. This is the sinful nature of humanity at work; we do not like to submit ourselves to every ordinance of man as unto God. We conveniently forget Paul wrote Romans 13 while the morally bankrupt Roman government rules the known world.
Further still, the Law was given to Israel so, as God’s chosen people for time and space, they would see how hideous their sin was. All law given to man by God reflects and reveals some of His character: His holiness, purity, and judgment. The Mosaic Law was given in writing to Israel and it drew a sharp contrast between the nature of God and that of man. Many theologians have compared this to the jeweler’s practice of displaying his choice diamonds on black velvet. Paul is painting a contrast here to give encouragement to the Christians, showing us how far greater than our sin is the grace of God that reigns in righteousness, conferring eternal life through faith in the Lord Jesus.
Paul addresses this same topic in Galatians 3, telling those who want to live under the Mosaic Law that its time and purpose have passed. As Jesus came in the fullness of time, the role of the Old Covenant wound down. Once Jesus came in the form of man and suffered for the sins of all the elect, the Old Covenant served no further purpose; the type gave way to the anti-type as the New Covenant was cut in the blood of the Lamb of God.