Why is the Church called “holy?”
The Church is holy (“set aside”) because she is sanctified by Jesus Christ through his passion, his doctrine, his prayer, and the Mysteries. As the Apostle explains: “Christ loved the Church and gave himself up for her in order to sanctify her, having purified her by the washing of water with the word, so that he might present her to himself in glory, without any spot or wrinkle or any such thing, but holy and flawless” (Eph 5:25–27). In his prayer to the Father for believers, the Lord petitions: “Sanctify them through your truth: your Word is truth. And for their sakes I sanctify myself, that they also may be sanctified in truth” (Joh 17:17–19).
For this reason, God’s people are properly called “saints” (“holy ones”): joined to Christ’s Body, they are set aside for a glorious purpose, to “be delivered from the bondage of decay into the glorious freedom of the children of God” (Rom 8:21; see Q370, Q542).
Because they have died to sin and risen to new life in Jesus Christ, Christians are called to be holy, as St Peter exhorts: “as he who called you is holy, you yourselves should also be holy in every aspect of your life, because it is written, ‘Be holy, for I am holy’” (1Pe 1:14–16). The members of the holy Church are thus at once “saints” and “called to be saints”: “To the saints who are at Ephesus, faithful in Christ Jesus” (Eph 1:1); “To the Church of God which is at Corinth. You are those who are sanctified in Christ Jesus, called to be saints, with all those who call upon the Name of our Lord Jesus Christ” (1Co 1:2; see Q266, Q402).
The term “saints” is also used in a specialized sense to refer to those faithful members of the Church who have gone to their rest in the Lord and whose intercession it is fitting to request by name in the divine services.
This determination, called “canonization” or, better, “glorification”, is essentially a matter of liturgical discipline: the recognition that a departed member of Christ may be publicly invoked and celebrated. Accordingly, this right belonged in early times to the local bishop (for local veneration), and today belongs to the synod or council of bishops of each autocephalous Church.
