Rules are like crutches. They are there to help us, but they are not our master, and we don't make keeping them the goal of our lives. Likewise, the Mosaic law was given by God for a limited role. In today's reading, Paul elaborates further on what the role is.
Jesus has forever freed us from the curse of the law; by faith in Him, we are justified by God.
He uses two examples to explain to the Galatians how the law relates to them and to the promise of God. First, he likens the law to a prison guard or sentry: ″We were held in custody under the law, locked up″ (Galatians 3:23). Prior to Christ's coming, like a guard, the law supervised us and restricted our behaviour. It laid out clearly God's standard of perfection and holiness. It also listed the punishments for disobedience, guiding us on how to behave in a manner pleasing to God. Although the law was given to the Jews, Gentiles cannot escape God's condemnation because the entire world is under the bondage of sin (v. 22).
However, the law's role is temporary; ″until the faith that was to come would be revealed″ (v. 23). What is this ″faith″ that Paul mentions? It probably refers to the gospel: how Christ enables us to receive the Abrahamic promise through faith in Him (v. 22). Once the gospel arrives-in the person, works, and resurrection of Christ-the role of the law is over. Jesus has forever freed us from the curse of the law; by faith in Him, we are justified by God. The guard can now be stood down, relieved of his duty, and recalled; his job is over.
Next, Paul uses a term-paidagogos-to describe the law (v. 24). The word means guardian, someone who attends to, watches over, and guides a young person in his development. The law is seen as preparing us for and pointing us to the coming of Christ. By revealing our sinfulness as well as our haplessness, the law awakens in us the need for a Saviour, so that ″we might be justified by faith″ (v. 24).
When Christ arrives, all who believe in Him have come of age (v. 25). The time of development is over. There is no need for either guard or guardian. From now on, all believers (″we″, v. 25), Jews or Gentiles, no longer live by the old order, but by faith in the Son of God, who loves us and died for us.
Paul's argument is clear: In the light of this truth, should we still assign a role to the law? No doubt it has a purpose and a limited role, but it cannot impart salvation. Only Jesus Christ can.