What does Acts 11:23 mean?

Barnabas (Acts 4:36–37), has been sent by the leadership of the Jerusalem church to validate that Gentiles in Syrian Antioch are really coming to a saving faith in Jesus. He's the perfect man for the job for several reasons. He is so gracious that he's given the name "son of encouragement." He's so fearless that he was the only one who would meet with Saul, the great persecutor of the church, to see if his conversion was real (Acts 9:26–27). And he's from Cyprus, which is just west of Antioch and the home of many of the Jesus-followers who are preaching to the Gentiles.

It takes a leader open to the Holy Spirit to enter a God-ordained situation and affirm it, instead of judging it and trying to control it. When Barnabas walks in, he doesn't see a bunch of former-pagans who need to change their sinful practices and become more like devout Jews (Acts 15:1–2). He sees the grace of God working in the world like He promised. He sees God's promise to Abraham—that his line would bless the world—come to fruition (Genesis 26:4). He understands that heaven celebrates when a sinner comes to Christ (Luke 15:7). And he experiences the fulfillment of Jesus' commission to the disciples to be His witnesses to the ends of the earth (Acts 1:8).

But he also sees that this job is far too big for him. We know, even now, how difficult it is to stay focused on our relationship with God. This church in Antioch includes Jews who see Jesus as the fulfillment but not replacement of Judaism, devout Gentiles who follow Judaism but haven't converted fully, and former pagan-Gentiles who have little understanding of the underlying Jewish traditions and laws. It's significant Barnabas "exhorted them all to remain faithful to the Lord"; only by concentrating on Jesus can they remain unified as a church.