CCC 865
© Libreria Editrice Vaticana Source: vatican.va
The Church is ultimately one, holy, catholic, and apostolic in her deepest and ultimate identity, because it is in her that "the Kingdom of heaven," the "Reign of God," Rev 19:6. already exists and will be fulfilled at the end of time. the kingdom has come in the person of Christ and grows mysteriously in the hearts of those incorporated into him, until its full eschatological manifestation. Then all those he has redeemed and made "holy and blameless before him in love," Eph 1:4. will be gathered together as the one People of God, the "Bride of the Lamb," Rev 21:9. "the holy city Jerusalem coming down out of heaven from God, having the glory of God." Rev 21:10-11. For "the wall of the city had twelve foundations, and on them the twelve names of the twelve apostles of the Lamb." Rev 21:14.
Read the full chapter 3. I Believe in the Holy Spirit ¶683–1065