Paul describes those whom the Son redeems as those under the law. By that phrase Paul characterizes all whom the Son came to redeem. Whether God’s law reaches us by special revelation as Jews (Rom 2:17–3:1) or by general revelation as Gentiles (Rom 2:12-16), it shows no partiality in its judgment: God’s law judges all to be under sin (Rom 2:6-11; 3:9-18). It is in that light that the Apostle would bring good news of great joy to all of us sinners, Jews and Gentiles alike. He would announce to us that, commissioned by His Father, God’s Son was born a servant to bring sinners release and rescue from sin and death.
But when the fullness of time had come, God sent forth his Son, born of woman, born under the law, 5 to redeem those who were under the law, so that we might receive adoption as sons. (Gal 4:4-5)
With the words born of woman in Gal 4:4, Paul had begun to reflect on the circumstances of Jesus’ birth. The next two phrases in Gal 4:4-5—born under the law, to redeem those who were under the law—bring into view not just another circumstance of His birth but also its purpose. Together both features point us again to the humiliation of God’s glorious eternal Son.
What does the Apostle mean by those words born under the law? Specifically, he means that the Son of the Father humbled Himself to be born a servant of the Lord His God (Phil 2:7). Born under Moses, the Son would live and learn obedience (Heb 5:8) under the educational rigors of the law. As a circumcised son of Abraham, the Son-born-servant would owe to His God and Father a perfect, personal, and perpetual obedience. Every detail of His life and death was under the pedagogical direction of God’s law, from His circumcision eight days after His birth (Luke 2:21), to His last Passover on the night before His death (Luke 22:7-23), to His submission to His Father’s will (Luke 22:41-42; John 17) and His honoring of His mother in His death (John 19:26-27). As a servant of the Lord, He humbly submitted Himself to the law of His God to fulfill all righteousness, down to the smallest letter and the smallest stroke of a pen. Comprehensively speaking, God’s law demanded a righteous man, a man who kept the divine commandments, a man qualified to live with God and to be the surety for His people. The Son, says Paul, became just such a man. Indeed, it was with His qualifications in mind that the law in its multiple dimensions (moral, civil, liturgical) was put into effect, for their fulfillment was to be found in Him. No wonder the author of Hebrews can say, when Christ came into the world, He said, … “Behold, I have come to do Your will, O God, as it is written of Me in the scroll of the book” (Heb 10:5, 7). What Child is this in the manger, then? He is the Son born under the law, born a servant of the Lord His God.