What does Acts 26:26 mean?
Paul is speaking to an audience of the governor and the leadership of Caesarea (Acts 25:23). Yet his primary focus is King Agrippa II (Acts 26:2–3). He is the son of Agrippa I who killed the apostle James, brother of John (Acts 12:1–2), and the great-grandson of Herod the Great (Matthew 2:1–4). Agrippa II was born shortly before the beginning of Jesus' ministry and he stayed in Rome for about twenty-five years, but he is well-versed in the Jewish culture and religion. And he's part Jewish, so he has a vested interest in the Christian application of the Jewish Scriptures.Specifically, Agrippa can see how the life, ministry, crucifixion, and resurrection of Jesus of Nazareth fulfilled prophecy. In fact, Paul is bold enough to assume Agrippa not only understands the prophecy, but that he believes it (Acts 26:27).
"Boldly" is from the Greek root word parrhēsiazomai and means "to speak freely or have confidence." To spread the message of Jesus "boldly" is a theme in the book of Acts and Paul's epistles. The apostles both prayed for and exhibited boldness in the early days of the church (Acts 4:13, 29, 31). Paul has bravely presented truths about Christ since he first accepted Him as the Messiah (Acts 9:28). He often writes to the churches with boldness (Romans 15:15; 2 Corinthians 3:12; Philemon 1:8) and also asks them to pray his boldness in proclaiming the gospel may continue (Ephesians 6:19–20).
"These things" refers to Jesus' fulfillment of prophecy (Acts 26:22–23) and the beginning of the Christian movement. "This has not been done in a corner" is a colloquial saying; Paul uses it to defend Christianity against the accusation that it is a "sect of the Nazarenes" (Acts 24:5), meaning an illegitimate variation of Judaism that is not authorized by the Roman government. The faith has been open, public, and honest about its beliefs and intentions.
The worship of Jesus as the Messiah is fully legitimized by Old Testament prophecy and has spread naturally and publicly; Paul does not lead an illegal cult. In addition, Agrippa has no reason to personally reject Christianity except for moral and political reasons. Perhaps because of his political position and his incestuous relationship with his sister, he politely declines (Acts 26:28).