What do we believe?
III. Only One Faith
172 Through the centuries, in so many languages, cultures, peoples and nations, the Church has constantly confessed this one faith, received from the one Lord, transmitted by one Baptism, and grounded in the conviction that all people have only one God and Father.  St. Irenaeus of Lyons, a witness of this faith, declared:
173 “Indeed, the Church, though scattered throughout the whole world, even to the ends of the earth, having received the faith from the apostles and their disciples. . . guards [this preaching and faith] with care, as dwelling in but a single house, and similarly believes as if having but one soul and a single heart, and preaches, teaches and hands on this faith with a unanimous voice, as if possessing only one mouth.” 
174 “For though languages differ throughout the world, the content of the Tradition is one and the same. the Churches established in Germany have no other faith or Tradition, nor do those of the Iberians, nor those of the Celts, nor those of the East, of Egypt, of Libya, nor those established at the centre of the world. . .”  The Church’s message “is true and solid, in which one and the same way of salvation appears throughout the whole world.” 
175 “We guard with care the faith that we have received from the Church, for without ceasing, under the action of God’s Spirit, this deposit of great price, as if in an excellent vessel, is constantly being renewed and causes the very vessel that contains it to be renewed.” 
58 Cf. Eph 4:4-6
59 St. Irenaeus, Adv. haeres. I, 10, 1-2: PG 7/1, 549-552.
60 St. Irenaeus, Adv. haeres. I, 10, 1-2: PG 7/1, 552-553.
61 St. Irenaeus, Adv. haeres. 5, 20, I: PG 7/2, 1177.
62 St. Irenaeus, Adv. haeres. 3, 24, I: PG 7/1, 966.
176 Faith is a personal adherence of the whole man to God who reveals himself. It involves an assent of the intellect and will to the self-revelation God has made through his deeds and words.
177 “To believe” has thus a twofold reference: to the person, and to the truth: to the truth, by trust in the person who bears witness to it.
178 We must believe in no one but God: the Father, the Son and the Holy Spirit.
179 Faith is a supernatural gift from God. In order to believe, man needs the interior helps of the Holy Spirit.
180 “Believing” is a human act, conscious and free, corresponding to the dignity of the human person.
181 “Believing” is an ecclesial act. the Church’s faith precedes, engenders, supports and nourishes our faith. the Church is the mother of all believers. “No one can have God as Father who does not have the Church as Mother” (St. Cyprian, De unit. 6: PL 4, 519).
182 We believe all “that which is contained in the word of God, written or handed down, and which the Church proposes for belief as divinely revealed” (Paul VI, CPG # 20).
183 Faith is necessary for salvation. the Lord himself affirms: “He who believes and is baptized will be saved; but he who does not believe will be condemned” ( Mk 16:16).
184 “Faith is a foretaste of the knowledge that will make us blessed in the life to come” (St. Thomas Aquinas. Comp. theol. 1, 2).
The answer to today’s question:
(CCC 182) We believe all that is written or handed down in the word of God and that the Church proposes for belief.