1. We have mentioned several times in previous catecheses the intervention of the Holy Spirit in the origin of the Church. It is good that we now dedicate a special catechesis to this beautiful and important theme.

It is Jesus himself who, before ascending to Heaven, says to the Apostles: "I will send upon you what my Father has promised; but you remain in the city, until you are clothed with power from on high" (Lk 24:49). Jesus intends to directly prepare the Apostles for the fulfilment of the "promise of the Father". The evangelist Luke repeats the same last recommendation of the Master also in the first verses of the Acts of the Apostles: "While he was at table with them, he commanded them not to depart from Jerusalem, but to wait until the promise of the Father was fulfilled" (Acts 1:4).

Throughout his messianic activity, Jesus, by preaching about the Kingdom of God, was preparing "the time of the Church", which was to begin after his departure. When this was near, he announced that the day was near when this time was to begin (cf. Acts 1:5), namely the day of the descent of the Holy Spirit. And looking into the future, he added: "You will receive power from the Holy Spirit who will come upon you, and you will be witnesses to me in Jerusalem and in all Judea and Samaria to the ends of the earth" (Acts 1:8).

2. When the day of Pentecost came, the Apostles, who together with the Mother of the Lord were gathered in prayer, were shown that Jesus Christ was acting in accordance with what he had announced: that "the promise of the Father" was being fulfilled. This was proclaimed by the first among the Apostles, Simon Peter, speaking to the assembly. Peter spoke, first recalling the death on the cross, and then moved on to the testimony of the resurrection and the outpouring of the Holy Spirit: "This Jesus God raised up, and we are all witnesses. Having therefore risen to the right hand of God, and having received from the Father the Holy Spirit whom he had promised, he poured out the Holy Spirit" (Acts 2:32-33).

Peter asserts from day one that the "promise of the Father" is fulfilled as the fruit of redemption, because it is by virtue of his cross and resurrection that Christ, the Son raised "to the right hand of God", sends forth the Spirit, as he had announced even before his passion at the moment of his farewell in the Upper Room.

3. The Holy Spirit thus began the mission of the Church established for all men. But we cannot forget that the Holy Spirit worked as the "unknown God" (cf. Acts 17:23) even before Pentecost. He worked in a special way in the old Covenant, enlightening and leading the chosen people on the road that led ancient history towards the Messiah. He operated in the messages of the prophets and in the writings of all inspired authors. He worked above all in the incarnation of the Son, as witnessed in the Gospel of the annunciation and the history of subsequent events connected to the coming into the world of the eternal Word who had assumed human nature. The Holy Spirit worked in and around the Messiah from the moment Jesus began his messianic mission in Israel, as is evident from the Gospel texts about the theophany at the moment of his baptism in the Jordan and his declarations in the synagogue in Nazareth. But from that same moment and throughout Jesus' life, the expectation and promises of a future, definitive coming of the Holy Spirit were accentuated. John the Baptist linked the mission of the Messiah to a new baptism "in the Holy Spirit". Jesus promised the believers in him "streams of living water": a promise recorded in John's Gospel, which explains it as follows: "This he said referring to the Spirit that the believers in him would receive; for there was not yet the Spirit, because Jesus had not yet been glorified" (John 7: 39). On the day of Pentecost, Christ, having now been glorified after the final fulfilment of his mission, caused the "rivers of living water" to gush forth from his bosom and poured out the Spirit to fill the Apostles and all believers with divine life. These could thus be "baptised into one Spirit" (cf. 1 Cor 12:13). And this was the beginning of the growth of the Church.

4. As the Second Vatican Council writes, "Christ sent the Holy Spirit from the Father, that he might accomplish his work of salvation from within and stimulate the Church to develop. Undoubtedly the Holy Spirit was at work in the world even before Christ was glorified. But it was on the day of Pentecost that it was poured out upon the disciples, to remain with them for ever, and the Church officially appeared before the multitude and began through preaching, the spreading of the Gospel among the pagans, and finally the union of peoples in the universality of the faith was prefigured through the Church of the new Covenant, which in all languages expresses itself and all languages in love understands and comprehends, thus overcoming the Babelic dispersion" (Ad gentes, 4).

The conciliar text highlights what the action of the Holy Spirit in the Church consists of, starting from the day of Pentecost. It is a salvific, interior action, which at the same time expresses itself externally in the emergence of the community and institution of salvation. This community - the community of the first disciples - is all pervaded by love, which overcomes all differences and divisions of an earthly order. A sign of this is the Pentecostal event of an expression of faith in God that is comprehensible to all, despite the diversity of languages. The Acts of the Apostles attest to us that the people gathered around the Apostles, in that first public manifestation of the Church, said with wonder: 'Are not all these who speak Galileans? And how is it that we hear them each speaking our native tongue' (Acts 2:7-8).

5. The Church that was just born like that on the day of Pentecost, by the power of the Holy Spirit, immediately manifests itself to the world. It is not a closed community, but open - one might say wide open - to all nations "to the ends of the earth" (Acts 1:8). Those who enter this community, through Baptism, become by virtue of the Holy Spirit of truth witnesses of the good news, ready to pass it on to others. It is therefore a dynamic, apostolic community: the Church "in a state of mission".

The Holy Spirit Himself first "bears witness" to Christ (cf. Jn 15:26), and this witness pervades the souls and hearts of those who participate in Pentecost, who in turn become witnesses and proclaimers. The "tongues like tongues of fire" (Acts 2:3) above the heads of each of those present constitute the outward sign of the enthusiasm kindled in them by the Holy Spirit. This enthusiasm extends from the Apostles to their hearers, just as already on the first day after Peter's speech "about three thousand people joined in . . ." (Acts 2:41).

6. The whole book of the Acts of the Apostles is a great description of the action of the Holy Spirit at the beginning of the Church, which - as we read - "grew and walked in the fear of the Lord, filled with the comfort of the Holy Spirit" (Acts 9, 31). It is known that internal difficulties and persecutions were not lacking, and that the first martyrs occurred. But the Apostles were certain that it was the Holy Spirit who was guiding them. This awareness of theirs would somehow be formalised in the concluding sentence of the Jerusalem Council, whose resolutions begin with the words: "We have decided, the Holy Spirit and we . . ." (Acts 15:28). The community thus attested its consciousness that it was moving under the action of the Holy Spirit.

[Pope John Paul II, General Audience 2 October 1991]