Cornelius was a good fearing Roman centurion. Cornelius has the distinction of being the first fully Gentile Christian recorded in scripture.
Before Cornelius’s conversion, Jews and even Samaritans (half-Jews who worshipped the Lord somewhat differently) had become Christians—but the Bible does not record that any Gentiles had become Christians yet, due in part to the fact that Peter and the other apostles did not even realize they could.
But with Cornelius’s conversion, all that would change forever. Cornelius was a centurion—a Roman military officer—which would have normally put him at odds with Jews and perhaps many early Christians as well. But Cornelius had already demonstrated that God was at work in his life, because
“he gave generously to those in need and prayed to God regularly” (Acts 10:2).
One day God spoke to Cornelius and told him to send for the apostle Peter in another town about thirty miles away. Meanwhile, God was working in Peter’s heart as well, showing him by a vision that all people —Gentiles as well as Jews—can find forgiveness of sins in Jesus Christ.
When Cornelius’s men arrived at Peter’s house, Peter went with them and shared the gospel with Cornelius’s household. The Holy Spirit came upon the new believers, confirming that this was indeed a work of God.
Though the Old Testament places a great deal of emphasis on the Jews as the chosen people of God (Genesis 12:1–3), there are still some passages that could have made it clear to Peter that God desires for Gentiles to follow Him as well. Jonah is corrected by God for his lack of concern for the wicked people of Nineveh even when they repented (Jonah 4). Psalm 87 also celebrates that various foreign peoples will be counted among those who know the Lord and registered as residents of Jerusalem.