What does Acts 11:2 mean?

Until this point, probably less than ten years after Jesus ascended into heaven, the church has been comprised of almost all Jews and proselytes. Philip did evangelize a town in Samaria, and Peter and John validated their salvation (Acts 8:4–25). And Philip converted an Ethiopian official on his way home (Acts 8:26–40). Yet these were mostly examples of Gentiles seeking out the gospel, rather than Jewish Christians introducing them to it. For the most part, the church members practice Judaism. They believe Jesus is the Messiah and see Jesus-worship as a natural extension of their native faith.

Of the two major Jewish sects, Pharisees had an easier time accepting Jesus because the Sadducees categorically denied the resurrection of the dead. However, they maintained their rigid legalism and adherence to the Mosaic law. Those known as the "circumcision party" were probably originally Pharisees. They had a hard time accepting that Gentiles could be accepted into the church without also converting fully to Judaism—that is, the males would have to be circumcised. They held these beliefs so tightly, they dared to attack Peter, the preeminent apostle of the church. Later, they will have even more trouble with Paul (Galatians 2:11–14; Philippians 3:2; Titus 1:10).

The "circumcision party's" hesitancy in accepting that salvation is by grace, through faith, and not from works (Ephesians 2:8–9) causes major disruptions in the early church (Acts 15). But their resistance also gives the early church leaders the opportunity to solidify the importance of grace in Christian theology. Considering Jesus' harsh words and warnings to the Pharisees during His public ministry (Matthew 23:1–36), it's only by the grace of God any of them were saved to begin with.