The last two chapters of Acts deal with Paul going to Rome. In Acts 19:21 Paul expressed his desire to go to Rome and in this chapter this journey begins. The Lord has promised he would witness for Him in Rome (Acts 23:11). Luke (c.f. Acts 21:8) and Aristarchus join Paul in this journey.
Chapters 27-28 include a long narration of Paul sea travel to Rome. Why did Luke write such a long account instead of a summary as he did often in the book of Acts? Several reasons are suggested:
1. Luke follows the patter of Greek writers who wrote exciting events including sea travels. This adds balance to the long speeches given in Acts. Luke's writing is very elegant in Greek (Witherington, Acts).
2. Luke shows that his writing is more credible since he takes part in this event. He not only researched the information in Acts but also had first hand experience.
3. Luke shows the sovereignty of God as he narrates how Paul arrived to Rome in spite of the circumstances. God was in control and was God's plan.
God is sovereign and will fulfill his purpose for each one of us and for his church. It doesn't matter what circumstances we go through, He is with us. He will use as well among those who don't believe in Him. Our witness may not bring the salvation of all who listen, but we will be an encouragement to all. God is glorified through our faithfulness.