"We have never even heard that there is a Holy Spirit" (Acts 19:3).
As Paul expanded his ministry from Corinth, he discovered a group of believers in Ephesus who knew of the baptism of John but had not yet heard about the Holy Spirit. John's baptism was about repentance, but he spoke of another baptism, not just of with water but with fire and the Holy Spirit.
How many lifelong Christians have yet to hear about the promise of the Spirit as the second wind of the their development in the faith? It is one thing to consider that we have left behind sin at baptism. It is another to believe that we are empowered by the Spirit to live a life of holiness and love that transcends keeping the commandments. The story of Pentecost is about ordinary men and women who felt totally inadequate and unworthy being transformed by God to do amazing things.
Jesus knew his disciples would have to go through failure and doubt before they could understand the gift of the Holy Spirit. They had to be vessels emptied of pride and self-reliance before the Spirit could indwell and empower them. The Spirit does not replace or override our natural gifts, but perfects them with grace to work on a scale we could not imagine. Like the five loaves and two fish a child offered to feed a hungry crowd in the wilderness, whatever we bring to God will be multiplied to meet the need.
The days between Ascension and Pentecost are a time of prayer and expectation. Open your hearts to what God wants to do through us as church. Pentecost was the Jewish celebration of harvest. A great harvest of goodness is ready to be gathered into God. We are the workers chosen to share this labor of divine love.