142By his Revelation, “the invisible God, from the fullness of his love, addresses men as his friends, and moves among them, in order to invite and receive them into his own company.” DV 2; cf. Col 1:15; 1 Tim 1:17; Ex 33:11; Jn 15:14-15; Bar 3:38 (Vulg.) The adequate response to this invitation is faith.

143By faith, man completely submits his intellect and his will to God. Cf. DV 5. With his whole being man gives his assent to God the revealer. Sacred Scripture calls this human response to God, the author of revelation, “the obedience of faith”. Cf. Rom 1:5; 16:26.

144To obey (from the Latin ob-audire, to “hear or listen to”) in faith is to submit freely to the word that has been heard, because its truth is guaranteed by God, who is Truth itself. Abraham is the model of such obedience offered us by Sacred Scripture. The Virgin Mary is its most perfect embodiment.

145The Letter to the Hebrews, in its great eulogy of the faith of Israel’s ancestors, lays special emphasis on Abraham’s faith: “By faith, Abraham obeyed when he was called to go out to a place which he was to receive as an inheritance; and he went out, not knowing where he was to go.” Heb 11:8; cf. Gen 12:1-4. By faith, he lived as a stranger and pilgrim in the promised land. Cf. Gen 23:4. By faith, Sarah was given to conceive the son of the promise. And by faith Abraham offered his only son in sacrifice. Cf. Heb 11:17.

146Abraham thus fulfills the definition of faith in Hebrews 11:1: “Faith is the assurance of things hoped for, the conviction of things not seen”: Heb 11:1. “Abraham believed God, and it was reckoned to him as righteousness.” Rom 4:3; cf. Gen 15:6. Because he was “strong in his faith”, Abraham became the “father of all who believe”. Rom 4:11,18; 4:20; cf. Gen 15:5.

147The Old Testament is rich in witnesses to this faith. The Letter to the Hebrews proclaims its eulogy of the exemplary faith of the ancestors who “received divine approval”. Heb 11:2, 39. Yet “God had foreseen something better for us”: the grace of believing in his Son Jesus, “the pioneer and perfecter of our faith”. Heb 11:40; 12:2.

148The Virgin Mary most perfectly embodies the obedience of faith. By faith Mary welcomes the tidings and promise brought by the angel Gabriel, believing that “with God nothing will be impossible” and so giving her assent: “Behold I am the handmaid of the Lord; let it be [done] to me according to your word.” Lk 1:37-38; cf. Gen 18:14. Elizabeth greeted her: “Blessed is she who believed that there would be a fulfillment of what was spoken to her from the Lord.” Lk 1:45. It is for this faith that all generations have called Mary blessed. Cf. Lk 1:48.

149Throughout her life and until her last ordeal Cf. Lk 2:35. when Jesus her son died on the cross, Mary’s faith never wavered. She never ceased to believe in the fulfillment of God’s word. And so the Church venerates in Mary the purest realization of faith.

150Faith is first of all a personal adherence of man to God. At the same time, and inseparably, it is a free assent to the whole truth that God has revealed. As personal adherence to God and assent to his truth, Christian faith differs from our faith in any human person. It is right and just to entrust oneself wholly to God and to believe absolutely what he says. It would be futile and false to place such faith in a creature. Cf. Jer 17:5-6; Ps 40:5; 146:3-4.

151For a Christian, believing in God cannot be separated from believing in the One he sent, his “beloved Son”, in whom the Father is “well pleased”; God tells us to listen to him. Mk 1:11; cf. 9:7. The Lord himself said to his disciples: “Believe in God, believe also in me.” Jn 14:1. We can believe in Jesus Christ because he is himself God, the Word made flesh: “No one has ever seen God; the only Son, who is in the bosom of the Father, he has made him known.” Jn 1:18. Because he “has seen the Father”, Jesus Christ is the only one who knows him and can reveal him. Jn 6:46; cf. Mt 11:27.

152One cannot believe in Jesus Christ without sharing in his Spirit. It is the Holy Spirit who reveals to men who Jesus is. For “no one can say “Jesus is Lord”, except by the Holy Spirit“, 1 Cor 12:3. who “searches everything, even the depths of God. . No one comprehends the thoughts of God, except the Spirit of God.” 1 Cor 2:10-11. Only God knows God completely: we believe in the Holy Spirit because he is God.

The Church never ceases to proclaim her faith in one only God: Father, Son and Holy Spirit.

153When St. Peter confessed that Jesus is the Christ, the Son of the living God, Jesus declared to him that this revelation did not come “from flesh and blood”, but from “my Father who is in heaven”. Mt 16:17; cf. Gal 1:15; Mt 11:25. Faith is a gift of God, a supernatural virtue infused by him. “Before this faith can be exercised, man must have the grace of God to move and assist him; he must have the interior helps of the Holy Spirit, who moves the heart and converts it to God, who opens the eyes of the mind and ‘makes it easy for all to accept and believe the truth.’” DV 5; cf. DS 377; 3010.

154Believing is possible only by grace and the interior helps of the Holy Spirit. But it is no less true that believing is an authentically human act. Trusting in God and cleaving to the truths he has revealed is contrary neither to human freedom nor to human reason. Even in human relations it is not contrary to our dignity to believe what other persons tell us about themselves and their intentions, or to trust their promises (for example, when a man and a woman marry) to share a communion of life with one another. If this is so, still less is it contrary to our dignity to “yield by faith the full submission of. . . intellect and will to God who reveals”, Dei Filius 3:DS 3008. and to share in an interior communion with him.

155In faith, the human intellect and will cooperate with divine grace: “Believing is an act of the intellect assenting to the divine truth by command of the will moved by God through grace.” St. Thomas Aquinas, STh II-II,2,9; cf. Dei Filius 3:DS 3010.

156What moves us to believe is not the fact that revealed truths appear as true and intelligible in the light of our natural reason: we believe “because of the authority of God himself who reveals them, who can neither deceive nor be deceived”. Dei Filius 3:DS 3008. So “that the submission of our faith might nevertheless be in accordance with reason, God willed that external proofs of his Revelation should be joined to the internal helps of the Holy Spirit.” Dei Filius 3:DS 3009. Thus the miracles of Christ and the saints, prophecies, the Church’s growth and holiness, and her fruitfulness and stability “are the most certain signs of divine Revelation, adapted to the intelligence of all”; they are “motives of credibility” (motiva credibilitatis), which show that the assent of faith is “by no means a blind impulse of the mind”. Dei Filius 3:DS 3008-3010; Cf. Mk 16 20; Heb 2:4.

157Faith is certain. It is more certain than all human knowledge because it is founded on the very word of God who cannot lie. To be sure, revealed truths can seem obscure to human reason and experience, but “the certainty that the divine light gives is greater than that which the light of natural reason gives.” St. Thomas Aquinas, STh II-II,171,5,obj.3. “Ten thousand difficulties do not make one doubt.” John Henry Cardinal Newman, Apologia pro vita sua (London: Longman, 1878) 239.

158“Faith seeks understanding”: St. Anselm, Prosl. prooem.:PL 153,225A. it is intrinsic to faith that a believer desires to know better the One in whom he has put his faith, and to understand better what He has revealed; a more penetrating knowledge will in turn call forth a greater faith, increasingly set afire by love. The grace of faith opens “the eyes of your hearts” Eph 1:18. to a lively understanding of the contents of Revelation: that is, of the totality of God’s plan and the mysteries of faith, of their connection with each other and with Christ, the center of the revealed mystery. “The same Holy Spirit constantly perfects faith by his gifts, so that Revelation may be more and more profoundly understood.” DV 5. In the words of St. Augustine, “I believe, in order to understand; and I understand, the better to believe.” St. Augustine, Sermo 43,7,9:PL 38,257-258.

159Faith and science: “Though faith is above reason, there can never be any real discrepancy between faith and reason. Since the same God who reveals mysteries and infuses faith has bestowed the light of reason on the human mind, God cannot deny himself, nor can truth ever contradict truth.” Dei Filius 4:DS 3017. “Consequently, methodical research in all branches of knowledge, provided it is carried out in a truly scientific manner and does not override moral laws, can never conflict with the faith, because the things of the world and the things of faith derive from the same God. The humble and persevering investigator of the secrets of nature is being led, as it were, by the hand of God in spite of himself, for it is God, the conserver of all things, who made them what they are.” GS 36 § 1.

160The freedom of faith: “To be human, “man’s response to God by faith must be free, and. . . therefore nobody is to be forced to embrace the faith against his will. The act of faith is of its very nature a free act.” DH 10; cf. CIC, can. 748 § 2. “God calls men to serve him in spirit and in truth. Consequently they are bound to him in conscience, but not coerced. . . This fact received its fullest manifestation in Christ Jesus.” DH 11. Indeed, Christ invited people to faith and conversion, but never coerced them. “For he bore witness to the truth but refused to use force to impose it on those who spoke against it. His kingdom. . . grows by the love with which Christ, lifted up on the cross, draws men to himself.” DH 11; cf. Jn 18:37; 12:32.

161The necessity of faith: Believing in Jesus Christ and in the One who sent him for our salvation is necessary for obtaining that salvation. Cf. 16:16; Jn 3:36; 6:40 et al. “Since “without faith it is impossible to please [God]” and to attain to the fellowship of his sons, therefore without faith no one has ever attained justification, nor will anyone obtain eternal life ‘But he who endures to the end.’“ Dei Filius 3:DS 3012; cf. Mt 10:22; 24:13 and Heb 11:6; Council of Trent:DS 1532.

162Perseverance in faith: Faith is an entirely free gift that God makes to man. We can lose this priceless gift, as St. Paul indicated to St. Timothy: “Wage the good warfare, holding faith and a good conscience. By rejecting conscience, certain persons have made shipwreck of their faith.” 1 Tim 1:18-19. To live, grow and persevere in the faith until the end we must nourish it with the word of God; we must beg the Lord to increase our faith; Cf. Mk 9:24; Lk 17:5; 22:32. it must be “working through charity,” abounding in hope, and rooted in the faith of the Church. Gal 5:6; Rom 15:13; cf. Jas 2:14-26.

163Faith – the beginning of eternal life: Faith makes us taste in advance the light of the beatific vision, the goal of our journey here below. Then we shall see God “face to face”, “as he is”. 1 Cor 13:12; 1 Jn 3:2.

When we contemplate the blessings of faith even now, as if gazing at a reflection in a mirror, it is as if we already possessed the wonderful things which our faith assures us we shall one day enjoy. St. Basil, De Spiritu Sancto, 15,36:PG 32,132; cf. St. Thomas Aquinas, STh II-II,4,1.

164Now, however, “we walk by faith, not by sight”; 2 Cor 5:7. we perceive God as “in a mirror, dimly” and only “in part”. 1 Cor 13:12. Even though enlightened by him in whom it believes, faith is often lived in darkness and can be put to the test. The world we live in often seems very far from the one promised us by faith. Our experiences of evil and suffering, injustice and death, seem to contradict the Good News; they can shake our faith and become a temptation against it.

165It is then we must turn to the witnesses of faith: to Abraham, who “in hope. . . believed against hope”; Rom 4:18. to the Virgin Mary, who, in “her pilgrimage of faith”, walked into the “night of faith” LG 58; John Paul II, RMat 18. 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.” Heb 12:1-2.