Acts is the second half of the Gospel of Luke and primarily concerned with the actions of the apostles many of whom were direct disciples of Jesus in the gospels. In the conclusion of Luke and in the start of Acts we see the disciples soon to be apostles waiting for something unknown and unimaginable.
3 He presented himself alive to them after his suffering by many proofs, appearing to them during forty days and speaking about the kingdom of God. 4 And while staying with them he ordered them not to depart from Jerusalem, but to wait for the promise of the Father, which, he said, “you heard from me; 5 for John baptized with water, but you will be baptized with the Holy Spirit not many days from now.” Acts 1:3-5 ESV
Jesus has spent time with them and convinced them of his resurrection. Jesus has restored Peter and given him charge of the church (John 21:17)
15 “If you love me, you will keep my commandments. 16 And I will ask the Father, and he will give you another Helper, to be with you forever, 17 even the Spirit of truth, whom the world cannot receive, because it neither sees him nor knows him. You know him, for he dwells with you and will be in you. John 14:15-17 ESV
Jesus has been promising the Spirit to the disciples before his death and after the resurrection but God through his prophets has promised the Spirit to be in those who love him long in advance. While Jesus who is God in the flesh is powerful and amazing he is still finite in the sense that men are limited to time and space. The Holy Spirit will not be bound to those finite constraints. Jesus as always is allowing God’s prefect plan to unfold right in front of the disciples.
26 And I will give you a new heart, and a new spirit I will put within you. And I will remove the heart of stone from your flesh and give you a heart of flesh. 27 And I will put my Spirit within you, and cause you to walk in my statutes and be careful to obey my rules. Ezekiel 36:26-28 ESV
God is going to do what we are unable to do ourselves and that is transform our hearts. He will put into us his Holy Spirit who will act on our hearts and transform our desires and hopes. In anticipation of this big day Jesus has asked the apostles to stay in Jerusalem and wait for Him to act.
Before Jesus ascends there is an interesting interaction recorded here in Acts. It is great example of how the disciples still did not understand the plans and power of Christ to build the eternal kingdom. Jesus has just told them to wait for the Holy Spirit in Jerusalem but their questions pick right up where they left off in their thinking before Jesus died.
6 So when they had come together, they asked him, “Lord, will you at this time restore the kingdom to Israel?” 7 He said to them, “It is not for you to know times or seasons that the Father has fixed by his own authority. 8 But you will receive power when the Holy Spirit has come upon you, and you will be my witnesses in Jerusalem and in all Judea and Samaria, and to the end of the earth.” Acts 1:6-8 ESV
Jesus are you now going to destroy the Romans and restore Israel to power? This is what the disciples think they really wanted from Jesus. It is why Judas betrayed Jesus (John 13:29). It is why Peter was ready to go to war when Jesus was taken (John 18:10-11). But that was not God’s plan. God’s plan was not to enrich Judas or send Peter to war. God’s plan is grace and mercy here and now. God’s plan is to save mankind and restore our relationship with Him. God’s plan is just as he said through Ezekiel hundreds of years before to change the heart of men.
Acts 1:8 is the gospel charge from Jesus to the disciples once the promised Holy Spirit arrives and the same charge stands true for the church of today. It is a promise that Luke uses here “you will be” in the same way that Luke recorded Jesus’ words to the thief on the cross “you will be”. Jesus makes a promise about God’s plans and passion for saving mankind.
43 And he said to him, “Truly, I say to you, today you will be with me in Paradise.” Luke 23:43 ESV
8 But you will receive power when the Holy Spirit has come upon you, and you will be my witnesses in Jerusalem and in all Judea and Samaria, and to the end of the earth.” Acts 1:8 ESV
Will you be part of that promise to witness to anyone and everyone through the power of the Holy Spirit living inside?