Pentecost defined the Church and so we should know its definition! It is the day when Christians celebrate the coming of the Holy Spirit and the beginning of the church. When we understand how Pentecost is defined, we will celebrate Pentecost with the same enthusiasm as Christmas and Easter.
Acts 2 tells us that after Jesus’s ascension a group of 120 were praying together in an upper room in Jerusalem. In fulfillment of a prophecy from Joel 2:28-32, suddenly the Holy Spirit descended on them with a sound like a mighty rushing wind and tongues of fire (Acts 2:1-4). The Word was preached, 3,000 were converted (Acts 2:41), and the Church began. So, as Christmas is the birthday of Christ, Pentecost celebrates the birthday of the Church.
Pentecost explains the reason that it is for the good of Christians that Jesus ascended to the right hand of the Father (John 16:7). Sinclair Ferguson (57, 71-72) summarizes:
Pentecost publicly marks the transition from the old to the new covenant, and signifies the commencement of the ‘now’ of the day of salvation (2 Cor 6:2). It is the threshold of the last days, and inaugurates the new era. . . Now as the bond of union to God, the Spirit indwells all who believe as the Spirit of the LORD Jesus Christ. This is a development of epochal proportion. The Spirit who was present and active at Christ’s conception as the head of the new creation . . . now indwells disciples in this specific identity. This is the meaning of our Lord’s words, otherwise impossible to comprehend: ‘It is for your good that I am going away’ (John 16:7).
Quotes from several other theologians help us better appreciate the importance of Pentecost:
At Pentecost believers experienced a transition from an old covenant experience of the Holy Spirit to a more powerful, new covenant experience of the Holy Spirit (Grudem, Systematic Theology, 722).
It was then that, through the coming of the Spirit, the minds of Christ’s followers were enriched with unprecedented illumination (1 John 2:20); their wills strengthened . . . with contagious animation (Acts 4:13,19, 20, 33; 5:29) and their hearts flooded with warm affection to a previously unprecedented degree (Acts 2:44-47; 3:6; 4:32).” (Hendriksen, Commentary on Mark, 41).
Formerly isolation, every man for himself; now organic union of all the members under their one Head: this is the difference between the days before and after Pentecost. The essential fact of Pentecost consisted in this, that on that day the Holy Spirit entered for the first time into the organic body of the Church, and individuals came to drink, not each by himself, but all together in organic union. Abraham Kuyper, The Holy Spirit, 133.
The baptism of the Spirit is the work which joins Christians together in a common bond of church relationship. It unites them, giving them an organic oneness. It provides them with a sense of mutual love, and sets before them a common purpose. It is because of this Christians, wherever they meet, feel an immediate closeness of friendship. They are of one group, a part in one grand enterprise. Leon Wood, The Holy Spirit in the Old Testament, 74-75.
Originally, the term “pentecost” was derived from a Greek word meaning 50th and referenced the 50th day after the Passover. But with the Pentecost of Pentecosts when the church was born marks an amazing new epoch in God’s unfolding plan of redemption (Acts 2:1).
See also Pentecost: When Babel Was Turned Upside Down
Credit for some of thoughts and wording in this article to M.C. Tenney’s article, “Pentecost,” in The Evangelical Dictionary of Theology edited by Elwell.