Galatians 4:1-7
Brethren, as long as the heir is a child, he differeth nothing from a servant, though he be Lord of all: but is under tutors and governors until the time appointed by the father: so we also, when we were children, were serving under the elements of the world. But when the fullness of the time was come, God sent His Son, made of a woman, made under the law, that He might redeem them who were under the law, that we might receive the adoption of sons. And because you are sons, God hath sent the Spirit of His Son into your hearts, crying: Abba, Father. Therefore now he is not a servant, but a son; and if a son, an heir also through God.
Haydock
Verse 1. By the child, in this place, the apostle understands all the Jewish people, who, as long as they were under the childhood of the law, were subject to numerous restrictions, although they were the favorite children of God. But when the fulness of time came, they received the adoption of children, and were in possession of the liberty of the law of grace. They were no longer obliged to observe the legal rites. Whence the apostle wishes the conclusion to be drawn, that if persons once subject to the law were now exempt from it, how much more will those be excused from its yoke, who were never under its control. Calmet.
Verse 3. Under the elements of the world. S. Chrys. understands the exterior ceremonies and precepts of the law of Moses, with an allusion to the first elements or rudiments which children are taught. Wi.
Verse 4. The fulness of the time. That is, the time decreed by Divine Providence. — God sent his Son made of a woman, who took a true human body of his virgin Mother. — Under the law, as he was man, because he was pleased to make himself so. Wi.
Verse 6. Crying, Abba. That is, Father; Christ taught us in prayer to call God our Father, he having made us his adoptive sons by his grace, and heirs of heaven. Wi.
Denzinger
311: Christ, the Natural, not the Adopted Son of God
COUNCIL OF FRANKFURT 794 From the synodical epistle of the bishops of France to the Spaniards
… For in the beginning of your little book we have found written what you have laid down: “We confess and we believe that God, the Son of God before all ages without beginning, was begotten from the Father, co-eternal and consubstantial, not by adoption but by birth.” Likewise after a few words in the same place we read: “We confess and we believe that He was made from a woman, made under the law[cf. Gal. 4:4], that not by birth is He the Son of God but by adoption; not by nature but by grace.” Behold the serpent hiding among the fruit bearing trees of Paradise, that he may deceive every unwary one.…
794: On the Dispensation and Mystery of the Advent of Christ
Council of Trent SESSION VI (Jan. 13, 1547) Decree On Justification
Whereby it came to pass that the heavenly Father, “the Father of mercies and the God of all comfort” [2 Cor. 1:3], when that “blessed fullness of time” was come [Eph. 1:10; Gal. 4:4] sent to men Christ Jesus [can. 1], his Son, who had been announced and promised [cf. Gen. 49:10, 18], both before the Law and at the time of the Law to many holy Fathers, that He might both redeem the Jews, who were under the Law, and the “gentiles, who did not follow after justice, might attain to justice” [Rom. 9:30], and that all men “might receive the adoption of sons” [Gal. 4:5]. “Him God has proposed as a propitiator through faith in his blood, for our sins” [Rom. 3:25], and not for our sins only, but also for those of the whole world [1 John 2:2].