Like many good historians of antiquity, Luke (the author of Acts) offered an important prologue explaining the subject of his work. The book of Acts is the second of a two-volume work, continuing the subject of the Gospel of Luke (see Luke 1:1–14). The book picks up with “all that Jesus began to do and to teach” (v. 1) until His ascension, and then Luke continued to narrate Christ’s ministry through His Spirit-empowered church.
That purpose for Christ’s church is made clear in verse 8 of our text today: “But you will receive power when the Holy Spirit comes on you; and you will be my witnesses in Jerusalem, and in all Judea and Samaria, and to the ends of the earth.” Jesus ascended to heaven, promising to return. The Apostles were left with a clear command to be Christ’s “witnesses” throughout the world. That theme of Spirit-filled witness will be important throughout this month’s study; look for it!
Now commissioned by the Lord, the Apostles responded with obedience, faith, and preparation. Notice their obedience in returning to Jerusalem to wait, just as Christ commanded. See also their faith as they “joined together constantly” (v. 14) in anticipation of God’s Spirit. This was no solitary moment, but a continued perseverance together in prayer! Peter’s words demonstrated faith in seeing all these events as God’s fulfillment of His promises.
And finally, observe their preparation as they sought to replace Judas with a twelfth apostle. The loss of Judas required a replacement before they were to proceed to be Christ’s witnesses to the world. Obedient, faithful and prepared, the Apostles waited.