From the Homily "The Great Unknown" by St. Josemaria Escriva
Having just read in the Acts of the Apostles about Pentecost, the day when the Holy Spirit came down upon the Lord's disciples, we are conscious of being present at the great display of God's power with which the Church's life began to spread among all nations. The victory Christ achieved through his obedience, his offering of himself on the cross, and his resurrection – his triumph over death and sin – is revealed here in all its divine splendor.
The disciples, witnesses of the glory of the risen Christ, were filled with the strength of the Holy Spirit. Their minds and hearts were opened to a new light. They had followed Christ and accepted his teachings with faith, but they were not always able to fathom the full meaning of his words. The Spirit of truth, who was to teach them all things, had not yet come. They knew that Jesus alone could give them words of eternal life, and they were ready to follow him and to give their lives for him. But they were weak, and, in the time of trial, they fled and left him alone.
On Pentecost, all that is a thing of the past. The Holy Spirit, who is the Spirit of strength, has made them firm, strong, daring. The word of the apostles resounds forcefully through the streets of Jerusalem. The men and women who have come to the city from all parts of the world listen with amazement. "Parthians and Medes and Elamites, and inhabitants of Mesopotamia, Judea, and Cappadocia, Pontus and Asia, Phrygia and Pamphylia, Egypt and the parts of Libya about Cyrene, and visitors from Rome, Jews as well as proselytes, Cretans and Arabs, we have heard them speaking in our own languages of the wonderful works of God." These wonders, which take place before their own eyes, lead them to listen to the preaching of the apostles. The Holy Spirit himself, who is acting through our Lord's disciples, moves the hearts of their listeners and leads them to the faith.
St. Luke tells us that after St. Peter had spoken and proclaimed Christ's resurrection, many of those present came up to him and asked: "Brethren, what shall we do?" The apostle answered: "Repent and be baptized, every one of you, in the name of Jesus Christ, for the forgiveness of your sins; and you will receive the gift of the Holy Spirit." And, on that day, the sacred text tells us, about three thousand were added to the Church.
The solemn coming of the Holy Spirit on Pentecost was not an isolated event. There is hardly a page in the Acts of the Apostles where we fail to read about him and the action by which he guides, directs and enlivens the life and work of the early Christian community.
It is he who inspires St. Peter's preaching, who strengthens the faith of the disciples, who confirms with his presence the calling of the Gentiles, who sends Saul and Barnabas to the distant lands where they will open new paths for the teachings of Jesus.
In a word, his presence and doctrine are everywhere.