The Church is a sacrament because it is in Christ. But also because it is in the Spirit. As we saw earlier, Lumen Gentium wastes no time describing the theological nature of the Church, that it is in Christ like a sacrament, a sign and instrument. However, there’s more to be said.

To be in Christ, as we’ve seen, is to belong to God’s saving work, to belong to the history of salvation, so to speak. And it’s by that history — as told in Scripture and rehearsed in Lumen Gentium — that we are able to describe further the theological reality of our own experience as believers, the reality of the Holy Spirit dwelling within us.

Lumen Gentium puts it this way: “When the work which the Father gave the Son to do on earth was accomplished, the Holy Spirit was sent on the day of Pentecost in order that He might continually sanctify the Church, and thus, all those who believe would have access through Christ in one Spirit to the Father. He is the Spirit of Life, a fountain of water springing up to life eternal. To men, dead in sin, the Father gives life through Him, until, in Christ, He brings to life their mortal bodies” (LG 4). This, of course, is simply a rehearsal of Scripture, echoing the story of Pentecost (Acts 2:1-3), Jesus’s teaching in the John’s Gospel (Jn 4:14; 7:37-38), and Pauline teaching (Eph 2:18; Rom 8:10-11).

What’s remarkable, however, is Lumen Gentium’s claim that this rehearsed biblical story remains ongoing in us, in the Church. The Spirit given at Pentecost still dwells within in us, “continually” sanctifying the Church. That is, the Holy Spirit knows no ascension. And thus, as Lumen Gentium continues, “The Spirit dwells in the Church and in the hearts of the faithful, as in a temple.” And what the Spirit does is guide the Church (as Jesus said in Jn 16:13) in “the way of all truth,” continually restoring the Church in the “freshness of youth,” drawing the Church ever nearer its Spouse, the risen Bridegroom Jesus Christ (LG 4). The Spirit keeps the Church oriented toward its final heavenly goal, the heavenly Jerusalem; the Spirit keeps the Church aflame with desire for its final union, expressed in the final prayer of the New Testament — “Amen. Come, Lord Jesus!” (Rev 22:20).

But notice how the Spirit accomplishes this renewing, orienting work in the Church — “in communion and in works of ministry.” Lumen Gentium teaches that the Spirit “equips and directs” the Church with “hierarchical and charismatic gifts,” which he adorns with his “fruits” (LG 4). That is, we believe that the Spirit enlivens the Church both in its visible structures and ministries as well as in the hearts of all believers being sanctified. We believe the Holy Spirit is given assuredly and always to the Church’s hierarchical structure, to its clergy — bishops, priests and deacons. We believe, therefore, that our polity, our clerical structure, is divinely given. This will be explored further when considering the sacrament of Holy Orders and the papacy; suffice it to say at this point, though, that this is a fundamental claim — that the Church’s hierarchical structure of bishops, priests and deacons, a structure that belongs essentially to the mission of God and to the organic nature of the Church, cannot replaced. This claim is distinctly Catholic, shared though by the Orthodox Churches and even some Protestant traditions. This is why in Catholicism you’ll never see things like “executive pastors” or any other different forms of ecclesiastical organization, no matter how more efficient those different structures may be. It’s also why arguments surrounding leadership and hierarchy in Catholicism get so theological so quickly. Because we believe that even the visible structures of the Church belong to its nature as sacrament, enlivened by the Holy Spirit “continually.”

But, of course, one mustn’t think the Holy Spirit dwells among and enlivens only the hierarchy of the Church. Even though that may sometimes seem to be the case, it never is; about that, the Church’s teaching has always been clear. Charismatic gifts belong to whomever the Spirit wills, to all the holy. The presence of the Spirit in the Church — present not just in the hierarchy but in all the saints — guarantees God’s sovereignty over the Church. The Holy Spirit dwells in all God’s people, not just clergy. In the faithful nun or monk. In the faithful parent. In the old lady, warrior at prayer, praying her rosary before Mass, who scares you a little. And it’s that spiritual fact — the fact of Pentecost — that makes for the joy and suffering, the tension, conflict and creativity of the Church. It’s what makes the Church so beautiful and sometimes so strange, giving the Church “the freshness of youth.” It’s also why one shouldn’t put too much store in polls or surveys suggesting the demise of the Church; such headlines make the rounds from time to time as if on schedule. Important though they may be, of course, they are no cause for despair. And that’s because the Holy Spirit remains — always has and always will — sustaining the Church “uninterruptedly” (LG 4).

And finally, it helps to recall for what purpose we believers live in the Church in Christ in the Spirit — so that we may be formed individually and together into Christ, “redeemed” and “re-molded into a new creation,” Lumen Gentium teaches, echoing St. Paul (LG 7; 2 Cor 5:17). That’s what the Holy Spirit, continually dwelling in the Church, does: he builds up the body of Christ, in the unity of faith and in knowledge of the Son, into the full stature of Christ (Eph 4:12-13). This is nothing other than the mission for glory for which Jesus prayed in John 17; it’s just now we see more clearly how this mission for glory is also the Church and its mission — calling in Christ by the Spirit all believers, sisters and brothers “together from all nations, mystically the components of His own Body” (LG 7). This thing we call the Catholic Church of Jesus Christ.

Father Joshua J. Whitfield is pastor of St. Rita Catholic Community in Dallas and author of “The Crisis of Bad Preaching” (Ave Maria Press, $17.95) and other books. Read more from the series here.