Read this week's lectionary readings here.
44 While Peter was still saying these things, the Holy Spirit fell on all who heard the word.
How did the witnesses know the Holy Spirit had done this?
46 For they were hearing them speaking in tongues and extolling God.
What was striking about this, aside from the fact that it was obviously a miracle? What was amazing about it, to people who were regularly amazed by such deeds of the Holy Spirit?
45 the believers from among the circumcised who had come with Peter were amazed, because the gift of the Holy Spirit was poured out even on the Gentiles
What was the conclusion based on this act of the Holy Spirit?
46 Then Peter declared,
47 "Can anyone withhold water for baptizing these people, who have received the Holy Spirit just as we have?"
48 And he commanded them to be baptized in the name of Jesus Christ
Or, as those who later heard Peter retell the entire story concluded: "Then to the Gentiles also God has granted repentance that leads to life" (Acts 11:18)
By the way, I encourage you to go through Acts 10 and 11 several times and read through it carefully. The entire story is retold several times from person to person. Each telling focuses on different details. All of them are important for a full understanding of what God is telling us in this story, but of course I would say that the main focus is the above: God has granted to Gentiles also the privilege of repenting from sin and receiving life in Jesus.
Thank God, because I am a Gentile.