What does Acts 10:2 mean?

Cornelius is a Roman centurion stationed in Caesarea Maritima, the headquarters of Herod Agrippa I. His job is to protect the king and put down any Jewish rebellion that would threaten Rome's authority over the Jews. But he worships the Jewish God. He is not identified as a proselyte; proselyte men must be circumcised. They must also be recognized as Jews, as Ruth was (Ruth 1:16). Instead, Cornelius is described as a "God-fearer."

Emperor worship and the pantheon of capricious Roman gods left something to be desired for many Gentiles in the Roman Empire. Some gravitated to Judaism on the basis of reason and experience. However, Judaism's invisible God and esoteric practices also tempted people who were merely looking for something mystical. Grifters, like Elymas (Acts 13:4–12) and the Jewish sons of Sceva (Acts 19:11–20), used this spiritual hunger for their own gain. Some Romans became converts to Mithraism and some, like the centurion in Capernaum (Matthew 8:5–13) were drawn to Judaism.

Cornelius is not the first centurion to earn the respect of Jews for his giving nature (Acts 10:22). In Capernaum, Jewish elders came to Jesus on behalf of a centurion, asking that Jesus would heal the centurion's servant. They said, "He is worthy to have you do this for him, for he loves our nation, and he is the one who built us our synagogue" (Luke 7:4–5). The centurion showed his faith in Jesus by assuming Jesus could heal at a distance (Luke 7:1–10).