In the first book, O Theophilus, I have dealt with all that Jesus began to do and teach, (Acts 1:1, ESV)
Luke describes his first book (Luke) as what Jesus began to do and teach, suggesting that Acts, his second book, is what Jesus continued to do and teach. In Luke, Jesus does it in person, in Acts He does it through the church. Acts is not the story of what Jesus' followers decided to do with his legacy, it's the story of what He is doing through them. It's Jesus' church and He's the one building it.