Catechism of the Catholic Church
737 The mission of Christ and the Holy Spirit is brought to completion in the Church, which is the Body of Christ and the Temple of the Holy Spirit. This joint mission henceforth brings Christ's faithful to share in his communion with the Father in the Holy Spirit. The Spirit prepares men and goes out to them with his grace, in order to draw them to Christ. The Spirit manifests the risen Lord to them, recalls his word to them and opens their minds to the understanding of his Death and Resurrection. He makes present the mystery of Christ, supremely in the Eucharist, in order to reconcile them, to bring them into communion with God, that they may "bear much fruit." 132
738 Thus the Church's mission is not an addition to that of Christ and the Holy Spirit, but is its sacrament: in her whole being and in all her members, the Church is sent to announce, bear witness, make present, and spread the mystery of the communion of the Holy Trinity (the topic of the next article):
All of us who have received one and the same Spirit, that is, the Holy Spirit, are in a sense blended together with one another and with God. For if Christ, together with the Father's and his own Spirit, comes to dwell in each of us, though we are many, still the Spirit is one and undivided. He binds together the spirits of each and every one of us, . . . and makes all appear as one in him. For just as the power of Christ's sacred flesh unites those in whom it dwells into one body, I think that in the same way the one and undivided Spirit of God, who dwells in all, leads all into spiritual unity. 133
739 Because the Holy Spirit is the anointing of Christ, it is Christ who, as the head of the Body, pours out the Spirit among his members to nourish, heal, and organize them in their mutual functions, to give them life, send them to bear witness, and associate them to his self-offering to the Father and to his intercession for the whole world. Through the Church's sacraments, Christ communicates his Holy and sanctifying Spirit to the members of his Body. (This will be the topic of Part Two of the Catechism.)
740 These "mighty works of God," offered to believers in the sacraments of the Church, bear their fruit in the new life in Christ, according to the Spirit. (This will be the topic of Part Three.)
741 "The Spirit helps us in our weakness; for we do not know how to pray as we ought, but the Spirit himself intercedes with sighs too deep for words." 134 The Holy Spirit, the artisan of God's works, is the master of prayer. (This will be the topic of Part Four.)
742 "Because you are sons, God has sent the Spirit of his Son into our hearts, crying, 'Abba! Father!"' (Gal 4:6).
743 From the beginning to the end of time, whenever God sends his Son, he always sends his Spirit: their mission is conjoined and inseparable.
744 In the fullness of time the Holy Spirit completes in Mary all the preparations for Christ's coming among the People of God. By the action of the Holy Spirit in her, the Father gives the world Emmanuel "God-with-us" (Mt 1:23).
745 The Son of God was consecrated as Christ (Messiah) by the anointing of the Holy Spirit at his Incarnation (cf.Ps 2:6-7).
746 By his Death and his Resurrection, Jesus is constituted in glory as Lord and Christ (cf. Acts 2:36). From his fullness, he poured out the Holy Spirit on the apostles and the Church.
747 The Holy Spirit, whom Christ the head pours out on his members, builds, animates, and sanctifies the Church. She is the sacrament of the Holy Trinity's communion with men.
English Translation of the Cathechism of the Catholic Church for the United States of America © 1997, United States Catholic Conference, Inc.