The Jewish festival of Pentecost is important for understanding the events of Acts 2. The Feast of Weeks or Shavuot celebrates the first fruits of the harvest. It happens fifty days after Passover (seven weeks) in the late spring / early summer. This festival included an offering of two loaves made with the wheat given in the first fruit offering (Lev 23:15–16; Deut 16:9).
For first-century Jews, Shavout was a declaration of “God’s ownership of the land and his grace in bringing forth food” (Sanders, Judaism, 139). The book of Ruth is read during this festival. That Ruth takes place during the wheat harvest may be the reason, but Ruth is not only a gentile convert to Judaism, she is the ancestor of King David. “There may also be a messianic significance in the choice of this work, i.e., that all the world will turn to Judaism eventually” (The Encyclopedia of Judaism; Leiden: Brill, 2000, 1:43). Since Acts begins the story of the Gospel beginning in Jerusalem and eventually going out to the whole world, this background may be significant. A significant problem for this view is our lack of certainty that Ruth was read at Pentecost in the first century. Even if it was, would Luke be aware of the reading, and would he want to tease out any messianic significance for reading Ruth at the Feast of Weeks.
According The Book of Jubilees, Pentecost was the day on which Moses was given the Law (cf. Tobit 2:1, 2 Macc 12:32). Although the Book of Exodus does not make this clear, there is a tradition that the Israelites arrived at Mount Sinai 50 days after the first Passover (Exod 19:1). Some scholars (Knox, Snaith) see a connection between this tradition and the gift of the Holy Spirit. Since Moses gave out the Law to Israel on this day, Jesus gives the Holy Spirit to the church. Joseph Fitzmyer suggested Luke was aware of the tradition since there are some indirect allusions to the giving of the Law in Acts 2, such as the image of fire descending from heaven (Exod 19:18). For some, the descent of the Spirit as “tongues of fire” alludes to the theophany at Sinai.
However, as Keener points out, there is no scholarly consensus on the meaning of Pentecost in this passage (Acts, 1:784). There are some parallels with a covenant renewal ceremony (Jubilees 6.17) or traditions about Pentecost in the (potentially later) Targumim. Keener concludes Luke use of Pentecost as a festival has no more significance to his narrative than providing large crowds and a short interval after Passover (Acts 1:787).
It is likely the first fruits of the harvest refers to those who receive the Holy Spirit in Acts 2. The new age has begun and the Holy Spirit has come for the first time. But there are two other potential Pentecosts in the book of Acts. In Acts 10 the Holy Spirit falls on Cornelius, a God-Fearing Gentile and he speaks in tongues just as the Jewish believers do in Acts 2. Peter makes this point himself in Acts 10:47: the Gentiles in Cornelius’ home received the Holy Spirit “just as we have.”
There is a third reference to Pentecost in Acts 20:16. Paul wants to return to Jerusalem before Pentecost if possible. This was a dangerous journey, especially since Paul wanted to deliver the collection from the Gentile churches at Pentecost. By delivering a gift to the poor in Jerusalem the Gentile churches demonstrate that they too have received the Holy Spirit. Paul’s return to Jerusalem at Pentecost is calculated to highlight his harvest among the Gentiles. That there are three references to Pentecost are not unexpected since Luke repeats important events three times several times in Acts (Cornelius’ conversion, Paul’s conversion, the rejection of Israel, etc.)
Whatever the intended imagery, the day represents the largest crowd in the Temple area since Passover fifty days before. Peter and the other apostles will be able to preach to large crowds of Jews gathered to worship God in the Temple (Acts 2-3).
What is there in Peter’s sermon that makes some use of this Pentecost imagery? Why did God choose Pentecost for the outpouring of the Spirit?
Bibliography: W. L. Knox, Acts, (NCB, Oxford: Clarendon, 1967), 80-84; N. Snaith, “Pentecost, the Day of Power,” ExpTim 43 (1931-32): 379-80; Mark J. Olson, “Pentecost,” ABD 5:222.