What does Acts 26:22 mean?

Caesarea Maritima was the Roman capital of Judea and Samaria. Paul is there speaking to Governor Festus, Roman army tribunes, and city leaders about why the Sanhedrin wants him dead. In the past, Paul mentioned it was because he believed in the resurrection of the dead (Acts 24:21). That worked for the previous governor, Felix, because Felix had a good understanding of the Jewish religion and knew that the Pharisees, the most common type of Jewish religious leader, all believed in the resurrection. Festus, however, has only been governor a few weeks and knows little about the Jewish culture or religion, so this defense won't make sense.

To that end, Paul points out that the Sanhedrin also vilifies him for spending so much time with Gentiles. Jesus chose him to spread the offer of forgiveness of sins and reconciliation with God to the Gentiles, and that is what Paul has spent the past few decades doing (Acts 26:20–21). In fact, he is with Gentiles so much he was falsely accused of bringing one into the temple, which is why he is in custody now (Acts 21:27–36).

But Paul is not primarily addressing his defense to the Gentiles in the room. He is focused on King Agrippa II (Acts 26:2–3, 19). As the great-grandson of Herod the Great (Matthew 2:1–4), Agrippa is a mixture of Arabian, Edomite (Genesis 36:1), and Jewish, among other ethnicities. He knows the Mosaic law and he believes the prophets of the Old Testament (Acts 26:27). Jesus promised that Paul would evangelize before kings, and Paul is taking advantage of this opportunity (Acts 9:15).

The Old Testament prophesied that the Messiah of the Jews would bring life to the Gentiles (Isaiah 42:6; 49:6; 60:3; Daniel 7:14). Agrippa knows these prophecies and believes them, although he probably never imagined they would be fulfilled by a carpenter from Nazareth. Still, there's no indication that he acts on this understanding and accepts Jesus as his savior.