§790
Creed › … › Paragraph 2. the Church - People of God, Body of Christ, Temple of the Holy Spirit
"One Body"
Believers who respond to God's word and become members of Christ's Body, become intimately united with him: "In that body the life of Christ is communicated to those who believe, and who, through the sacraments, are united in a hidden and real way to Christ in his Passion and glorification." This is especially true of Baptism, which unites us to Christ's death and Resurrection, and the Eucharist, by which "really sharing in the body of the Lord, . . . We are taken up into communion with him and with one another."
Source: Catechism of the Catholic Church (Vatican.va)