CCC 422 ‘But when the time had fully come, God sent forth his Son, born of a woman, born under the law, to redeem those who were under the law, so that we might receive adoption as sons.’1 This is ‘the gospel of Jesus Christ, the Son of God’:’2 God has visited his people. He has fulfilled the promise he made to Abraham and his descendants. He acted far beyond all expectation – he has sent his own ‘beloved Son’.3

CCC 484 The Annunciation to Mary inaugurates “the fullness of time”,4 the time of the fulfillment of God’s promises and preparations. Mary was invited to conceive him in whom the “whole fullness of deity” would dwell “bodily”.5 The divine response to her question, “How can this be, since I know not man?”, was given by the power of the Spirit: “The Holy Spirit will come upon you.”6

CCC 488 “God sent forth his Son”, but to prepare a body for him,7 he wanted the free co-operation of a creature. For this, from all eternity God chose for the mother of his Son a daughter of Israel, a young Jewish woman of Nazareth in Galilee, “a virgin betrothed to a man whose name was Joseph, of the house of David; and the virgin’s name was Mary”:8
The Father of mercies willed that the Incarnation should be preceded by assent on the part of the predestined mother, so that just as a woman had a share in the coming of death, so also should a woman contribute to the coming of life.9

CCC 527 Jesus’ circumcision, on the eighth day after his birth,10 is the sign of his incorporation into Abraham’s descendants, into the people of the covenant. It is the sign of his submission to the Law11 and his deputation to Israel’s worship, in which he will participate throughout his life. This sign prefigures that “circumcision of Christ” which is Baptism.12

CCC 531 During the greater part of his life Jesus shared the condition of the vast majority of human beings: a daily life spent without evident greatness, a life of manual labor. His religious life was that of a Jew obedient to the law of God,13 a life in the community. From this whole period it is revealed to us that Jesus was “obedient” to his parents and that he “increased in wisdom and in stature, and in favor with God and man.”14

CCC 580 The perfect fulfillment of the Law could be the work of none but the divine legislator, born subject to the Law in the person of the Son.15 In Jesus, the Law no longer appears engraved on tables of stone but “upon the heart” of the Servant who becomes “a covenant to the people”, because he will “faithfully bring forth justice”.16 Jesus fulfills the Law to the point of taking upon himself “the curse of the Law” incurred by those who do not “abide by the things written in the book of the Law, and do them”, for his death took place to redeem them “from the transgressions under the first covenant”.17

CCC 683 “No one can say ‘Jesus is Lord’ except by the Holy Spirit.”18 “God has sent the Spirit of his Son into our hearts, crying, ‘Abba! Father!”’19 This knowledge of faith is possible only in the Holy Spirit: to be in touch with Christ, we must first have been touched by the Holy Spirit. He comes to meet us and kindles faith in us. By virtue of our Baptism, the first sacrament of the faith, the Holy Spirit in the Church communicates to us, intimately and personally, the life that originates in the Father and is offered to us in the Son.
Baptism gives us the grace of new birth in God the Father, through his Son, in the Holy Spirit. For those who bear God’s Spirit are led to the Word, that is, to the Son, and the Son presents them to the Father, and the Father confers incorruptibility on them. And it is impossible to see God’s Son without the Spirit, and no one can approach the Father without the Son, for the knowledge of the Father is the Son, and the knowledge of God’s Son is obtained through the Holy Spirit.20

CCC 689 The One whom the Father has sent into our hearts, the Spirit of his Son, is truly God.21 Consubstantial with the Father and the Son, the Spirit is inseparable from them, in both the inner life of the Trinity and his gift of love for the world. In adoring the Holy Trinity, life-giving, consubstantial, and indivisible, the Church’s faith also professes the distinction of persons. When the Father sends his Word, he always sends his Breath. In their joint mission, the Son and the Holy Spirit are distinct but inseparable. To be sure, it is Christ who is seen, the visible image of the invisible God, but it is the Spirit who reveals him.

CCC 693 Besides the proper name of “Holy Spirit,” which is most frequently used in the Acts of the Apostles and in the Epistles, we also find in St. Paul the titles: the Spirit of the promise,22 the Spirit of adoption,23 the Spirit of Christ,24 the Spirit of the Lord,25 and the Spirit of God26 – and, in St. Peter, the Spirit of glory.27

CCC 702 From the beginning until “the fullness of time,”28 the joint mission of the Father’s Word and Spirit remains hidden, but it is at work. God’s Spirit prepares for the time of the Messiah. Neither is fully revealed but both are already promised, to be watched for and welcomed at their manifestation. So, for this reason, when the Church reads the Old Testament, she searches there for what the Spirit, “who has spoken through the prophets,” wants to tell us about Christ.29
By “prophets” the faith of the Church here understands all whom the Holy Spirit inspired in the composition of the sacred books, both of the Old and the New Testaments. Jewish tradition distinguishes first the Law (the five first books or Pentateuch), then the Prophets (our historical and prophetic books) and finally the Writings (especially the wisdom literature, in particular the Psalms).30

CCC 1265 Baptism not only purifies from all sins, but also makes the neophyte “a new creature,” an adopted son of God, who has become a “partaker of the divine nature,”31 member of Christ and co-heir with him,32 and a temple of the Holy Spirit.33

CCC 1695 “Justified in the name of the Lord Jesus Christ and in the Spirit of our God,”34 “sanctified. .. [and] called to be saints,”35 Christians have become the temple of the Holy Spirit.36 This “Spirit of the Son” teaches them to pray to the Father37 and, having become their life, prompts them to act so as to bear “the fruit of the Spirit”38 by charity in action. Healing the wounds of sin, the Holy Spirit renews us interiorly through a spiritual transformation.39 He enlightens and strengthens us to live as “children of light” through “all that is good and right and true.”40

CCC 1972 The New Law is called a law of love because it makes us act out of the love infused by the Holy Spirit, rather than from fear; a law of grace, because it confers the strength of grace to act, by means of faith and the sacraments; a law of freedom, because it sets us free from the ritual and juridical observances of the Old Law, inclines us to act spontaneously by the prompting of charity and, finally, lets us pass from the condition of a servant who “does not know what his master is doing” to that of a friend of Christ – “For all that I have heard from my Father I have made known to you” – or even to the status of son and heir.41

CCC 2766 But Jesus does not give us a formula to repeat mechanically.42 As in every vocal prayer, it is through the Word of God that the Holy Spirit teaches the children of God to pray to their Father. Jesus not only gives us the words of our filial prayer; at the same time he gives us the Spirit by whom these words become in us “spirit and life.”43 Even more, the proof and possibility of our filial prayer is that the Father “sent the Spirit of his Son into our hearts, crying, ‘Abba! Father!’”44 Since our prayer sets forth our desires before God, it is again the Father, “he who searches the hearts of men,” who “knows what is the mind of the Spirit, because the Spirit intercedes for the saints according to the will of God.”45 The prayer to Our Father is inserted into the mysterious mission of the Son and of the Spirit.

CCC 2777 In the Roman liturgy, the Eucharistic assembly is invited to pray to our heavenly Father with filial boldness; the Eastern liturgies develop and use similar expressions: “dare in all confidence,” “make us worthy of. .. ” From the burning bush Moses heard a voice saying to him, “Do not come near; put off your shoes from your feet, for the place on which you are standing is holy ground.”46 Only Jesus could cross that threshold of the divine holiness, for “when he had made purification for sins,” he brought us into the Father’s presence: “Here am I, and the children God has given me.”47
Our awareness of our status as slaves would make us sink into the ground and our earthly condition would dissolve into dust, if the authority of our Father himself and the Spirit of his Son had not impelled us to this cry. .. ‘Abba, Father!’. .. When would a mortal dare call God ‘Father,’ if man’s innermost being were not animated by power from on high?48

1 Gal 4:4-5.
2 Mk 1:1.
3 Mk 1:11; cf. Lk 1:5, 68.
4 Gal 4:4.
5 Col 2:9.
6 Lk 1:34-35 (Greek).
7 Gal 4:4; Heb 10:5.
8 Lk 1:26-27.
9 LG 56; cf. LG 61.
10 Cf. Lk 2:21.
11 Cf. Gal 4:4.
12 Cf. Col 2:11-13.
13 Cf. Gal 4:4.
14 Lk 2:51-52.
15 Cf. Gal 4:4.
16 Jer 31:33; Is 42:3, 6.
17 Gal 3:13; 3:10; Heb 9:15.
18 1 Cor 12:3.
19 Gal 4:6.
20 St. Irenaeus, Dem. ap. 7: SCh 62, 41-42.
21 Cf. Gal 4:6.
22 Cf. Gal 3:14; Eph 1:13.
23 Rom 8:15; Gal 4:6.
24 Rom 8:9.
25 2 Cor 3:17.
26 Rom 8:9, 14; 15:19; 1 Cor 6:11; 7:40.
27 1 Pet 4:14.
28 Gal 4:4.
29 Cf. 2 Cor 3:14; Jn 5:39, 46.
30 Cf. Lk 24:44.
31 2 Cor 5:17; 2 Pet 1:4; cf. Gal 4:5-7.
32 Cf. l Cor 6:15; 12:27; Rom 8:17.
33 Cf. l Cor 6:19.
34 2 Cor 6:11.
35 1 Cor 1:2.
36 Cf. 1 Cor 6:19.
37 Cf. Gal 4:6.
38 Gal 5:22, 25.
39 Cf. Eph 4:23.
40 Eph 5:8, 9.
41 Jn 15:15; cf. Jas 1:25; 2:12; Gal 4:1-7.21-31; Rom 8:15.
42 Cf. Mt 6:7; 1 Kings 18:26-29.
43 Jn 6:63.
44 Gal 4:6.
45 Rom 8:27.
46 Ex 3:5.
47 Heb 1:3; 2:13.
48 St. Peter Chrysologus, Sermo 71, 3: PL 52, 401 CD; cf. Gal 4:6.