CATECHISM OF THE CATHOLIC CHURCH
SECOND EDITION

Paragraphs 827–831

827 "Christ, 'holy, innocent, and undefiled,' knew nothing of sin, but came only to expiate the sins of the people. The Church, however, clasping sinners to her bosom, at once holy and always in need of purification, follows constantly the path of penance and renewal." All members of the Church, including her ministers, must acknowledge that they are sinners. In everyone, the weeds of sin will still be mixed with the good wheat of the Gospel until the end of time. Hence the Church gathers sinners already caught up in Christ's salvation but still on the way to holiness:

The Church is therefore holy, though having sinners in her midst, because she herself has no other life but the life of grace. If they live her life, her members are sanctified; if they move away from her life, they fall into sins and disorders that prevent the radiation of her sanctity. This is why she suffers and does penance for those offenses, of which she has the power to free her children through the blood of Christ and the gift of the Holy Spirit.

828 By canonizing some of the faithful, i.e., by solemnly proclaiming that they practiced heroic virtue and lived in fidelity to God's grace, the Church recognizes the power of the Spirit of holiness within her and sustains the hope of believers by proposing the saints to them as models and intercessors. "The saints have always been the source and origin of renewal in the most difficult moments in the Church's history." Indeed, "holiness is the hidden source and infallible measure of her apostolic activity and missionary zeal."
829 "But while in the most Blessed Virgin the Church has already reached that perfection whereby she exists without spot or wrinkle, the faithful still strive to conquer sin and increase in holiness. And so they turn their eyes to Mary": in her, the Church is already the "all-holy."
830 The word "catholic" means "universal," in the sense of "according to the totality" or "in keeping with the whole." The Church is catholic in a double sense:

First, the Church is catholic because Christ is present in her. "Where there is Christ Jesus, there is the Catholic Church." In her subsists the fullness of Christ's body united with its head; this implies that she receives from him "the fullness of the means of salvation" which he has willed: correct and complete confession of faith, full sacramental life, and ordained ministry in apostolic succession. The Church was, in this fundamental sense, catholic on the day of Pentecost and will always be so until the day of the Parousia.

831 Secondly, the Church is catholic because she has been sent out by Christ on a mission to the whole of the human race:

All men are called to belong to the new People of God. This People, therefore, while remaining one and only one, is to be spread throughout the whole world and to all ages in order that the design of God's will may be fulfilled: he made human nature one in the beginning and has decreed that all his children who were scattered should be finally gathered together as one. . . . The character of universality which adorns the People of God is a gift from the Lord himself whereby the Catholic Church ceaselessly and efficaciously seeks for the return of all humanity and all its goods, under Christ the Head in the unity of his Spirit.