Adoption As Sons: Galatians 3:23-4:5, especially vss. 4, 5: "But when the fullness of the time had come, God sent forth His Son, born of a woman, born under the Law, to redeem those who were under the Law, that we might receive the adoption as sons."
In meditating on the teaching of St. Paul in Galatians, one gains a keen awareness of how the life in Christ fulfills the Faithful, in contrast to any legalistic religion based on rules alone. Among the various descriptive images by which the Apostle contrasts faith in Christ with reliance on the Law is "inheritance through adoption as sons of God" versus "bond-slavery under the stewardship of the Law" (vss. 1-3).
Yes, under the Mosaic Law, the People of God were consigned to a way of life "under guard by the Law" to await the "coming of faith" (vs. 23). The Apostle himself was raised in that manner of life, and he knew it first hand. He draws a vivid portrait of life under bondage to Law. The descriptive words, "under guard" and "kept" in vs. 23, suggest effective spiritual imprisonment. This is the way one English translation renders the verse: "we were held prisoners by the law, locked up" [NIV, vs. 23]. The Apostle's point is that the role of Law is custodial - rules control every action of the person. The versions that use the word "tutor" (vs. 24 NAS) for "paidagogos" in the original miss the point that in ancient culture "paidagogos" were themselves generally slaves, responsible for protecting children from accident or attack. These custodians often taught children manners, and their instruction often was rather harsh. Their primary role was confining and restraining in order to protect. Those who revert to legalism as a way of life elect rules to dominate and manage their lives. They are "kept" by commandments.
All through today's reading, the Apostle emphasizes that living under the strictures of law need only apply "until Christ" (vs. 23). For those who are "sons of God" (vss. 25,26), who have been "baptized into Christ" (vs. 27), who have "put on Christ" (vs. 27), who are "Abraham's seed" (vs. 29), the time of managed childhood should be over (vs. 3).
The "fullness of the time [has] come" (vs. 4). We are redeemed from that virtual slavery (vs. 5). The advent of God in the flesh, "born of a woman," brings about two necessary conditions for ending the domination of the Law over one's life: first, the true alternative to bondage under Law had to "be revealed" (vs. 23). The Seed to Whom the promises were given had to come so that God's People could believe in Him rather than in the Law (vs. 22), allowing the alternative of "faith" to be "revealed" (vs. 23). Second, it is necessary to believe rightly in the Lord Jesus Christ. Faith in Him is required. Notice at this point that the Apostle immediately mentions Baptism. In the Church, Baptism and faith are like dynamic equivalents: one who has faith is Baptized. To be Baptized expresses faith in Christ, which is why this Holy Mystery is called, "putting on Christ" (vs. 27).
What happens when we put on Christ, when we are Baptized into Him? Childhood is ended. The time of pure custody under law should cease. We are no longer "slaves" (vs. 1), but adopted sons (vs. 5). Relationship with God changes from obedience to Law into a relationship with Christ, our God, in Whom we live and Who lives in us. He assists us and guides us as a most merciful Enabler and Helper, not as a slave-master. Also, let us not think of discipleship as mere "learning of information," which distorts true relationship with Christ. Throughout the New Testament, the word "disciple" has a meaning closer to "trainee." The Lord Himself trains us through a process, which includes trying, failing (or succeeding), reflecting on our efforts, and re-practicing. This is how we grow in Christ - we gain capacity through His illumination.
We who have put on Thee, O Christ, beseech Thee, make us victors even unto the end.