Last Sunday, we began our new study in the Book of Acts. To re-cap, in Acts 1:1-15, Luke chronicles Jesus’ final instructions to His disciples, His bodily ascension into heaven, and the followers' return to Jerusalem. Jesus promises the coming of the Holy Spirit and outlines their mission to be witnesses to the ends of the earth, before returning to an upper room to pray.
We finished up chapter 1, beginning at verse 15. Here we see Peter addressing the betrayal of Jesus. He stands before the gathered community, believers, numbering about 120 people—and brings up the fate of Judas Iscariot. He explains that Judas's betrayal and subsequent death were the fulfillment of Old Testament prophecy.
Peter notes that a replacement must be chosen to complete the original group of the twelve apostles. The candidate must have been a constant companion of the group from the time of John’s baptism through the day of Jesus’ ascension. The assembly puts forward two men who fit the description: Joseph (called Barsabbas, also known as Justus) and Matthias.
Rather than voting, the disciples pray to God, acknowledging His knowledge of all human hearts, and ask Him to reveal which of the two men He has chosen. They then cast lots, and the lot falls to Matthias, who is officially added to the eleven apostles.