Chapter 26 starts with Agrippa giving Paul permission to speak in his defense.
First Paul addressed Agrippa thanking him for being the one to hear his case. He told Agrippa he knew he was an expert in all the Jewish customs and controversies. (I imagine Paul felt comfortable Agrippa could see the truth and be fair in hearing and judging Paul's statements.)
Paul gave them his background also declaring the Jewish leaders were well aware of him and what he had done in the past. He spoke of being taught in the Jewish ways in Jerusalem. Also that he had been a member of the strictest Jewish sect, the Pharisees.
Paul went on to say he was on trial because of his hope in the fulfillment of God's promise to their ancestors and commented that the tribes of Israel worshipped God day and night because of that very promise. (God had made a promise, Israel believed it and worshipped God because of it. All his peers believed it but now he was on trial for something they all believed. This type of explanation seems to make their issues with Paul to be quite foolish.)
Paul asked them, "Why does it seem incredible to any of you that God can raise the dead?" (They believed in the Almighty God, Creator of all things so how could they find it hard to believe He could not raise a man from the dead?)
Paul continued by describing how he had earlier believed as they did. He persecuted everyone and anyone to stop the people from following Jesus the Nazarene. Even the leading priests in Jerusalem authorized his persecution of Jesus followers and believers. He persecuted, tormented and imprisoned Jesus believers and voted along with others for the death penalty for some. Paul had believers punished, and beaten in the synagogues in an effort to get them to curse Jesus. Paul was so determined to stop the growth of believers, he even went to foreign cities to persecute believers there.
Paul then shared his journey to Damascus with the authority granted him by the leading priests to persecute believers there. About noon, while on the road to Damascus he and his companions were enveloped in a light brighter than the sun. Paul said they all fell down and he heard a voice speaking to him in Aramaic. The voice said, "Saul, Saul (this happened back before Paul had believed in Christ and had used the name Saul. After his conversion he used the name Paul) why are you persecuting me? It is useless for you to fight against my will."
Paul asked the voice who he was and the Lord replied, "I am Jesus, the one you are persecuting. Now get to your feet! For I have appeared to you to appoint you as my servant and witness. You are to tell the world what you have seen and what I will show you in the future. (This mission to tell the world is aided by Paul's imprisonment and trials. If he had not been persecuted and charged by the leading priests the odds are slim he would have had the opportunity to speak of Jesus in front of as many of the people as he did such as Agrippa, Felix and Festus as well as all who gathered to hear the trials. They kept moving him from city to city and eventually to Rome to speak in front of the leaders there, even Caesar.) (Jesus continued) And I will rescue you from both your own people and the Gentiles. Yes, I am sending you to the Gentiles to open their eyes, so they may turn from darkness to light and from the power of Satan to God. Then they will receive forgiveness for their sins and be given a place among God's people, who are set apart by faith in me."
Paul told Agrippa, he obeyed that vision and preached in Damascus, Jerusalem, all Judea and to the Gentiles as he was instructed. He preached that they must repent of their sin and turn to God and prove they have changed by the good things they do. As he was preaching these things, he was arrested by some Jews in the Temple who tried to kill him. Paul went on to say that God had protected him as He promised right up to this very moment. (We can see God did that so His message would be spread near and far to both Jews and Gentiles.)
Paul declared he preached nothing but what was said would happen according to the prophets and Moses. Paul stated more clearly what that teaching was. It was the teaching that the Messiah would suffer and be the first to rise from the dead and by doing so He would announce God's light to the Jews and Gentiles. At that point Festus jumped in and shouted, "Paul, you are insane. Too much study has made you crazy!" Paul's response was that he was not insane but that what he taught was the sober truth. He mentioned that even King Agrippa was familiar with these things and went so far as to ask Agrippa if he believed the prophets but quickly added he knew he did.
Agrippa interrupted Paul and asked, "Do you think you can persuade me to become a Christian so quickly?" Paul answered him saying he wished all there would become like him, a follower of Jesus, only without the chains and that it didn't matter if it happened quickly or not.
Then Agrippa, the governor and Bernice left along with all the others. They talked about what they had heard and agreed Paul had not done anything worthy or death or imprisonment and could have gone free if he had not appealed to Caesar.
(When we read that he could have been set free, we might feel like Paul messed up, when in reality if he hadn't appealed to Caesar he would have been set free and all those in Rome who God planned to have hear his message may never have heard it. God's plan was unfolding so that all might one day hear the Good News.)