Acts 10 is vital to Luke's narrative outlining the expansion of Christianity beyond the bounds of Jerusalem. Consider the importance to Luke with these measurements. In the preceding chapter, Luke tells how Peter raised a woman from the dead. He covers the event in 5 verses. Acts 10 requires 48 verses! What in magnitude requires almost 10 times the amount of space. Answer - the conversion of the first Gentile convert, the Roman centurion, Cornelius. And the one responsible for the conversion is not the apostle to the Gentiles, Paul, but rather the Apostle Peter.
Chapter 10 shows how this momentous event is directed by the hand of God. For Luke, from his vantage point in time, it explains why the church was becoming predominantly Gentile (non-Jewish). If anyone were to accuse St. Paul of leading the church astray by bring unclean pagan into the faith, Luke's narrative sets the story straight. The church should welcome Gentiles because it is God's plan, coordinated through visions and trances.
Cornelius and his household even experienced a "second Pentecost" similar to Jewish believers. More about that in a later post.