After his resurrection, Jesus appeared to his disciples and instructed them for 40 days, after which he ascended to heaven. While with them, he said: “Do not leave Jerusalem, but wait for the gift my Father promised, which you have heard me speak about. For John baptized with water, but in a few days you will be baptized with the Holy Spirit” (Acts 1:4-5). That baptism of the Spirit would be called the birthday of the church.
Jesus’ words were fulfilled on the day of Pentecost. The disciples were filled with the Holy Spirit (Acts 2:4), and the apostle Peter preached his first sermon, urging the crowds to repent, to believe in Jesus Christ as their Messiah and to receive the gift of the Holy Spirit (verse 38). That very day, some 3,000 people were baptized as the people of God (verse 41). The church had begun.
The day called Pentecost is named after the Greek word pentekostos, which means 50th. It is the festival observed by Jews, Shavuoth, sometimes called in the Old Testament the Feast of Weeks (Exodus 34:22; Leviticus 23:15; Numbers 28:26; Deuteronomy 16:9-12). Other names for the day are the Feast of the Harvest and Day of First Fruits (Exodus 23:16; Numbers 28:26). Pentecost was to be observed in ancient Israel on the 50th day after the priest waved a selected sheaf of the first grain that had been harvested in the spring (Leviticus 23:15-21). Seven weeks elapsed between the day of the wave sheaf offering and the beginning of Pentecost, thus the name of the festival — the Feast of Weeks. This festival had come to signify for Jews the commemoration of the giving of the Law of Moses (the Torah) at Mount Sinai in the third month after the Exodus Passover (Exodus 20–24).
Perhaps the Holy Spirit came on the Jewish day of Shavuoth, or Pentecost, to signal that God had now moved to write the Law not on tables of stone, but in the hearts of his people through the Spirit (2 Corinthians 3). The indwelling Spirit, the Comforter or Advocate Jesus had sent, was replacing the external “schoolmaster” Law of Moses that had supervised ancient Israel’s worship under the old covenant (Galatians 3:23-25).
“If I am lifted up,” Jesus said, “I will draw all people to myself” (John 12:32). God had moved once and for all through his Son to rescue humanity from sin and death. The coming of the Spirit into human hearts and minds on that Day of Pentecost in the early 30s was God’s sign that in Christ he was creating a new people — a new Israel — an Israel of the Spirit (Galatians 6:16) that included Jews and Gentiles alike.
Pentecost or Whitsunday
Many Christians celebrate the coming of the Holy Spirit in worship activities on Pentecost, or as it is sometimes called, Whitsunday. This name is said to arise from the ancient practice of newly baptized individuals wearing white robes during this time. In the Christian liturgical year, Pentecost is the seventh Sunday after Easter and closes the Easter season.