20 Now the law came in [came in alongside] to increase the trespass, but where sin increased, grace abounded all the more,
Verses 20 and 21 address the question of how the Mosaic law fits into the previous argument. The Mosaic law has epochal significance in the argument. However, the law was not even necessary to condemn us, because the sin of Adam itself condemned us.
20 Now the law [Mosaic] came in [alongside] to increase the trespass [Adam’s original sin],
The only law Adam knew was the commandment not to eat of the fruit of the tree. He did not have the law of Moses. God chose not to give the Mosaic covenant to anyone before the time of Moses (Dt 5:3). The purpose of the Mosaic law was “to increase the trespass.” The law simply showed the magnitude of how we violate an absolutely holy God. This magnitude of violating God was a new thing with the law. It leaves man hopeless without the cross. This is the new principle introduced by the law.
The law came alongside grace to show the sinfulness of violating an absolute God. The words “came in” indicate that the law came in alongside the issue of Adam’s epoch sin. Paul set the law alongside sin and death, which “entered” human experience (v.12). The law increased sin into the nature of a trespass; it did not deliver people from sin. It only made sin manifest. The law had a secondary role in the issue at hand.
Ga 3:19 What purpose then does the law serve? It was added because of transgressions, till the Seed should come to whom the promise was made; and it was appointed through angels by the hand of a mediator.
The purpose of the law was to increase the trespass (singular). The singular “trespass” indicates the original sin of Adam. The “trespass” here is the trespass of Adam. The law thus can only condemn (4:15). There is a continuity between Adam’s sin and that of his descendants.
The law came in alongside sin. The law did not cause sin but brought out the true nature of sin so that it is manifest for what it truly is. The law makes sin a transgression. This put great emphasis on the need for God’s grace.
The law is a secondary issue in God’s plan; it is not an end in itself. Its purpose was that the trespass might increase, not to prevent sin. This “increase” was to make us aware of the seriousness of sin.
The law entered to increase our violation of God.
God calls us to a life of grace and to live before God’s pleasure. Because of that we need to see sin as a transgression or violation of God. There is no code whereby man can act with impunity before God. First, we need to be brought to the place of acknowledging our sin. God brings us to that point by showing how we fail to meet His standards.
Only when we realize that our only hope is in God’s grace through the cross can we come to the place of salvation. A mirror shows us that our face is dirty but it cannot cleanse our face. The law can show us we are sinful but it cannot save us from sin. Only the grace of God can do that.
Ro 3:20 Therefore by the deeds of the law no flesh will be justified in His sight, for by the law is the knowledge of sin.
Ga 3:10 For as many as are of the works of the law are under the curse; for it is written, “Cursed is everyone who does not continue in all things which are written in the book of the law, to do them.”
We must turn from our works and self-effort to God’s grace.