What does it mean for the Church to be “catholic (universal)”?
Q140 · (c) Exposition of the Creed
In the water of baptism, the Holy Spirit expels the spirit of division. The Church of Christ, the One Lord, should have one faith and one Holy Spirit, working within her, despite her diverse languages and cultures. No social barriers can deprive a genuine believer from being a member in the universal Church. Multilingualism and multiculturalism cannot negate the universality of the Church.
This universality is deeply felt by every believer. The Holy Spirit sanctifies the soul, body, mind, emotions, and all the talents and gifts of the believer. Not even death is able to overcome this characteristic of the Church, for the faithful who have departed become a for us cloud of witnesses that is not far from us, nor estranged from us. The apostle Paul says, “Therefore we also, since we are surrounded by so great a cloud of witnesses …” (Heb. 12:1). He also says, “raised us up together” (Eph. 2:6). Thus, the risen life has become ours in Christ Jesus. We are one — the departed with those who still struggle on earth — together with the generations yet to come. We are one family, one sanctified bride of the heavenly Bridegroom.
Whenever we see divisions within the human community, or the human family, then with a heart set aflame with love we ought to plead with the Holy Spirit to work in people’s hearts, that we might fulfil the words of the apostle Paul: “Endeavoring to keep the unity of the Spirit in the bond of peace. There is one body and one Spirit, just as you were called in one hope of your calling; one Lord, one faith, one baptism; one God and Father of all, who is above all, and through all, and in you all. But to each one of us grace was given according to the measure of Christ’s gift” (Eph. 4:3–7).
337 St. Ambrose of Milan, On the Holy Spirit 2.5.33, 36–37 (NPNF II/10:118–119) amended.