What does Acts 15:7 mean?

The church in Jerusalem, including the apostles, the elders, and James, the half-brother of Jesus, are debating whether Gentile Christians must convert to Judaism before worshiping the Messiah promised to the Jews. Earlier, some Jewish Christians from the sect of the Pharisees had gone to Syrian Antioch and challenged the authenticity of the Gentiles' salvation. Paul and Barnabas debated vehemently with these visitors from Judea, and the church in Syrian Antioch decided to send Paul, Barnabas, and others to the church in Jerusalem to see the apostles and elders about the question (Acts 15:1–6).

Now, Peter gives his testimony. He reminds the group of his interaction with the centurion Cornelius. After a symbolic vision that explained to Peter both non-kosher foods and Gentiles were acceptable to God, Peter was called to Cornelius' home. While Peter was still explaining the salvation offered by Jesus, the Holy Spirit fell on the centurion and his houseful of Gentiles—without baptism or circumcision (Acts 10). Peter's audience knows this story because Jews from this same group of Christian Pharisees condemned him for eating with Gentiles. Peter gave his account in detail, and when the Jerusalem church realized Gentiles had been saved, they glorified God (Acts 11:1–18).

Peter agrees with Paul, Barnabas, and the other representatives from the church in Syrian Antioch: a church whose membership is largely comprised of Gentiles who had not previously worshiped the Jewish God as Cornelius had. In fact, Peter goes on to say that even Jews were never able to fulfill the requirements of the Mosaic law. Everyone, Jew or Gentile, can only be saved through grace (Acts 15:10–11).

It is unclear how this meeting fits with Paul's account in Galatians 2. In that letter, Paul first describes how he and Barnabas went to Jerusalem to validate the message they had been giving to the Gentiles (Galatians 2:1–10). He then recounts an event when Peter was visiting Syrian Antioch and enjoying fellowship with the Gentile believers. When Pharisee-Christians came "from James," they shamed Peter and Barnabas into breaking that fellowship, presumably because of the long-standing assertion that Jews were not to eat with Gentiles (Galatians 2:11–14). It's to be hoped that the event in Antioch happened prior to this meeting, but if it didn't, we still have assurance that if Peter can be led astray by shame, God knows and forgives our weaknesses, as well.