One holy catholic and apostolic

Read the Catechism: Day 127

IN BRIEF

866 The Church is one: she acknowledges one Lord, confesses one faith, is born of one Baptism, forms only one Body, is given life by the one Spirit, for the sake of one hope (cf. Eph 4:3-5), at whose fulfillment all divisions will be overcome.
867 The Church is holy: the Most Holy God is her author; Christ, her bridegroom, gave himself up to make her holy; the Spirit of holiness gives her life. Since she still includes sinners, she is "the sinless one made up of sinners." Her holiness shines in the saints; in Mary she is already all-holy.
868 The Church is catholic: she proclaims the fullness of the faith. She bears in herself and administers the totality of the means of salvation. She is sent out to all peoples. She speaks to all men. She encompasses all times. She is "missionary of her very nature" (AG 2).
869 The Church is apostolic. She is built on a lasting foundation: "the twelve apostles of the Lamb" (Rev 21:14). She is indestructible (cf. Mt 16:18). She is upheld infallibly in the truth: Christ governs her through Peter and the other apostles, who are present in their successors, the Pope and the college of bishops.
870 "The sole Church of Christ which in the Creed we profess to be one, holy, catholic, and apostolic, ... subsists in the Catholic Church, which is governed by the successor of Peter and by the bishops in communion with him. Nevertheless, many elements of sanctification and of truth are found outside its visible confines"(LG 8).
Dig deeper: Scriptural and other references for today's section here.