When the great promise of the Spirit was fulfilled on the day of Pentecost, it was fulfilled not in reference to the apostles only.
The Spirit is as operative today in communicating the gospel to all who seek the truth as it was on the day of Pentecost anciently.
St. Peter announced the glad tidings of the Gospel to the people on the day of Pentecost, and converted, by the first Christian sermon, ever preached, three thousand - which formed the primitive Church.
From the first Day of Pentecost, the Holy Spirit has proven that He will only come to the degree that we have unity.
We do not need to wait for the Holy Spirit to come: he came on the day of Pentecost. He has never left the church.
Your Day Is Your Life
When you strip it of everything else, Pentecost stands for power and life. That's what came into the church when the Holy Spirit came down on the day of Pentecost.