Luke recorded that Jesus came to bring deliverance to the Jews and to the whole world (Luke 4:14-30). In his Gospel, Luke told the story of Jesus' personal ministry, primarily to the Jews. In Acts the emphasis is mainly on Jesus' ministry, through His apostles, to the Gentile world. As the mission to the Gentiles unfolds in Acts we can see that Luke took pains to show that the ministry to the Gentiles paralleled the ministry to the Jews. He did this by relating many things that the missionaries to the Gentiles did that were very similar to what the missionaries to the Jews did. This demonstrates that God was indeed behind both missions and that they are really two aspects of His worldwide plan to bring the gospel to all people and to build a worldwide church.
The present section of text (12:25-16:5) does more than just present the geographical expansion of the church into Asia Minor (modern western Turkey). Primarily it shows the legitimacy of dealing with Gentiles as Gentiles rather than through Judaism before and after their conversion. It becomes increasingly clear that the church and Judaism are two separate entities. God was not renewing the remnant in Israel and refreshing it with Gentile's who believed in Jesus. He was creating a new body: the church. This section culminates in the Jerusalem Council (ch. 15) in which the issue of the Gentiles' relationship to the church came to a head. The last verse (16:5) summarizes these events and issues.