Before we get to the answer we need to cover some basics: If I give you something because of what I promised, it is not because of your performance. If I give you something because of what you’ve done, it is not because of my promise. Paul is adamant in Galatians: either something comes by GRACE or WORKS; either it comes because of the giver’s promise or the receiver’s performance.
A gift-promise needs only to be believed to be received, but a law-wage must be obeyed to be received.
The promise by God to Abram is a covenantal promise and it is a covenant that relies in no way on Abram, but only on God.
Therefore, the law of Moses must have a different purpose!
As soon as redemption or salvation becomes based on performance, it can no longer be a free gift.
It is common for believers to begin their faith journey with Christ looking beyond themselves at “Christ…clearly…crucified” (Galatians 3:1), relying on God’s promise that Christ has taken our curse and blessed us. But as we journey, it is tempting and easy to look within ourselves at our “human effort” (3:3), resting in our own performance to give us the confidence of God’s acceptance. Doing this makes us radically insecure–it cuts away our assurance and prompts us to despair or get prideful.
So what is the purpose of the law then? Galatians 3:19…it was “added because of transgressions,” until Christ came. The law did not come to tell us about salvation, but about sin. Its main purpose is to show us our problem: we are law-breakers.
The law was never intended to “impart life” (3:21). The law makes us realize how morally helpless we are. We are not simply sinners, but prisoners of sin, helpless to free or cure ourselves.
The law has the power to show us we are not righteous; but it cannot give us the power to be righteous.
The law does its work to lead us toward recognition of our need for salvation by grace through Christ.
The law can no longer be viewed as a system of salvation. It no longer forces obedience through coercion and fear. When we grasp salvation-by-promise, our hearts are filled with gratitude and a desire to please and be like our Savior. The way to do that is through obeying the law! When we come to the law motivated by gratitude, we are better in our obedience to the law than we were when we thought obedience saved us.
Grateful joy is a motive that leads to more endurance in obedience than fearful compliance. Once we understood salvation by promise, we don’t obey God any longer for our sake, by using the law-salvation system to get things from God. We now obey God for His sake.
Law and grace work together in salvation. Everyone wants joy and acceptance but won’t admit the reality and severity of their sin. They will not allow the law to search and analyze their hearts. But unless we see how profoundly sinful we are, the message of salvation will not liberate and create joy.
In other words, unless we know how big our debt is, we can’t have any idea how big Christ’s payment cost Him. If we don’t realize how bad we are, the idea of grace will seem useless and never change us.
The law shows us as we really are. So the law points us to Christ as he really is: SAVIOR…the One who obeyed the law on our behalf and died in our place so we might receive the promise.