Acts is the second part of a two-part work. Its writer opens by reminding Theophilus of his first book, which told what Jesus began to do and to teach, and the Gospel of Luke is addressed to the same man. Acts takes up the story at the ascension and carries it about thirty years, from an upper room in Jerusalem to the capital of the empire.
The book follows the plan Jesus lays out before he ascends. His followers will bear witness first in Jerusalem, then through Judea and Samaria, and then out to the farthest nations. Chapters 1 to 7 stay in Jerusalem, chapters 8 to 12 move into Judea and Samaria, and chapters 13 to 28 carry the witness out among the nations.
Two men carry most of the story. Peter is the voice of the church in Jerusalem, before the crowds at the temple and before the council that tries to silence the apostles. Paul first appears as Saul, a persecutor of the church, and becomes its missionary to the nations.
The Holy Spirit drives the book. He fills the first disciples on the day of Pentecost and falls again on new believers in Samaria, in Caesarea and in Ephesus. He sends out missionaries, guides their road and speaks through prophets. Six times the writer pauses to report that the word of God kept spreading and the church kept growing, and each report closes one stage of the advance.
Halfway through the book, the apostles and elders gather in Jerusalem to answer whether Gentile believers must be circumcised and keep the law of Moses. They decide that Gentiles who turn to God are welcomed without circumcision, and James grounds the decision in the prophets' promise that the nations would seek the Lord. The Gentiles join what God had promised Israel. In city after city Paul goes first to the synagogue, and Jews and Gentiles come to faith side by side.
The book ends in Rome with Paul's trial still undecided. He lives for two years in a rented house under guard, welcomes everyone who comes to him and preaches the kingdom of God boldly and freely. The good news has reached the capital of the empire, on the road the first chapter set out.