169 Salvation comes from God alone; but because we receive the life of faith through the Church, she is our mother: "We believe the Church as the mother of our new birth, and not in the Church as if she were the author of our salvation." Because she is our mother, she is also our teacher in the faith.
837 "Fully incorporated into the society of the Church are those who, possessing the Spirit of Christ, accept all the means of salvation given to the Church together with her entire organization, and who - by the bonds constituted by the profession of faith, the sacraments, ecclesiastical government, and communion - are joined in the visible structure of the Church of Christ, who rules her through the Supreme Pontiff and the bishops. Even though incorporated into the Church, one who does not however persevere in charity is not saved. He remains indeed in the bosom of the Church, but 'in body' not 'in heart.'"
846 How are we to understand this affirmation, often repeated by the Church Fathers? Re-formulated positively, it means that all salvation comes from Christ the Head through the Church which is his Body:
Basing itself on Scripture and Tradition, the Council teaches that the Church, a pilgrim now on earth, is necessary for salvation: the one Christ is the mediator and the way of salvation; he is present to us in his body which is the Church. He himself explicitly asserted the necessity of faith and Baptism, and thereby affirmed at the same time the necessity of the Church which men enter through Baptism as through a door. Hence they could not be saved who, knowing that the Catholic Church was founded as necessary by God through Christ, would refuse either to enter it or to remain in it.
1277 Baptism is birth into the new life in Christ. In accordance with the Lord's will, it is necessary for salvation, as is the Church herself, which we enter by Baptism.
766 The Church is born primarily of Christ's total self-giving for our salvation, anticipated in the institution of the Eucharist and fulfilled on the cross. "The origin and growth of the Church are symbolized by the blood and water which flowed from the open side of the crucified Jesus." "For it was from the side of Christ as he slept the sleep of death upon the cross that there came forth the 'wondrous sacrament of the whole Church.'" As Eve was formed from the sleeping Adam's side, so the Church was born from the pierced heart of Christ hanging dead on the cross.
780 The Church in this world is the sacrament of salvation, the sign and the instrument of the communion of God and men.
http://www.scborromeo.org/ccc/p123a9p3.htm#III