Fully one fourth of the book of Acts is taken up with speeches – speeches we often read over without seeing their importance.
If they weren’t important, why would Luke include them? And if they are important, why are they important?
Even though some of Jesus’ teaching is found in Luke 4 – 9, the main focus of those chapters is on what Jesus did. Even though Jesus does a few miracles in Luke 9 – 19, the main focus of those chapters is on what Jesus taught. The speeches in Acts interrupt the story of Acts in order to emphasize the teaching of Acts, which is, by the way, the teaching of Jesus. While Luke tells the story of what Jesus began to do and teach, the book of Acts continues the story of Jesus’ words and deeds through His Church.
In Acts chapter two, themes we have already seen become focused and announced plainly: All that has happened with Jesus, and all that will now happen to and through his followers, is according to the purpose, plan, and work of God (that’s what the fulfillment of scripture is all about, as well as the resurrection story, coming and work of the Spirit, and the plain statement in verse 23). That these things are indeed the work of God is verified by those who have seen them – the witnesses (vss. 22, 32). This work of God has declared plainly the supremacy of Jesus: He is Lord and Christ (vs. 36). The hearers are guilty of rejecting the very one, the only one who can make salvation possible (vs. 23). And yet, as bad as things are, God still offers salvation to those who will repent and submit to Jesus (vss. 38, 40).
These themes get repeated in the rest of the speeches in this book, Luke’s way of emphasizing the truthfulness of what Theophilus had been taught.