CCC 146 Abraham thus fulfills the definition of faith in Hebrews 11:1: “Faith is the assurance of things hoped for, the conviction of things not seen”:1 “Abraham believed God, and it was reckoned to him as righteousness.”2 Because he was “strong in his faith”, Abraham became the “father of all who believe”.3

CCC 165 It is then we must turn to the witnesses of faith: to Abraham, who “in hope. .. believed against hope”;4 to the Virgin Mary, who, in “her pilgrimage of faith”, walked into the “night of faith”5 in sharing the darkness of her son’s suffering and death; and to so many others: “Therefore, since we are surrounded by so great a cloud of witnesses, let us also lay aside every weight, and sin which clings so closely, and let us run with perseverance the race that is set before us, looking to Jesus the pioneer and perfecter of our faith.”6

CCC 298 Since God could create everything out of nothing, he can also, through the Holy Spirit, give spiritual life to sinners by creating a pure heart in them,7 and bodily life to the dead through the Resurrection. God “gives life to the dead and calls into existence the things that do not exist.”8 And since God was able to make light shine in darkness by his Word, he can also give the light of faith to those who do not yet know him.9

CCC 706 Against all human hope, God promises descendants to Abraham, as the fruit of faith and of the power of the Holy Spirit.10 In Abraham’s progeny all the nations of the earth will be blessed. This progeny will be Christ himself,11 in whom the outpouring of the Holy Spirit will “gather into one the children of God who are scattered abroad.”12 God commits himself by his own solemn oath to giving his beloved Son and “the promised Holy Spirit. .. [who is] the guarantee of our inheritance until we acquire possession of it.”13

CCC 723 In Mary, the Holy Spirit fulfills the plan of the Father’s loving goodness. Through the Holy Spirit, the Virgin conceives and gives birth to the Son of God. By the Holy Spirit’s power and her faith, her virginity became uniquely fruitful.14

1 Heb 11:1.
2 Rom 4:3; cf. Gen 15:6.
3 Rom 4:11, 18; 4:20; cf. Gen 15:5.
4 Rom 4:18.
5 LG 58; John Paul II, RMat 18.
6 Heb 12:1-2. Article 2.
7 Cf. Ps 51:12.
8 Rom 4:17.
9 Cf. Gen 1:3; 2 Cor 4:6.
10 Cf. Gen 18:1-15; Lk 1:26-38. 54-55; Jn 1:12-13; Rom 4:16-21.
11 Cf. Gen 12:3; Gal 3:16.
12 Cf. In 11:52.
13 Eph 1:13-14; cf. Gen 22:17-19; Lk 1:73; Jn 3:16; Rom 8:32; Gal 3:14.
14 Cf. Lk 1:26-38; Rom 4:18-21; Gal 4:26-28.