While Paul was saying this in his defense, Festus said in a loud voice, "Paul, you are out of your mind! Your great learning is driving you mad." But Paul *said, "I am not out of my mind, most excellent Festus, but I utter words of sober truth. For the king knows about these matters, and I speak to him also with confidence, since I am persuaded that none of these things escape his notice; for this has not been done in a corner. King Agrippa, do you believe the Prophets? I know that you do."
Acts 26:24-27

Paul was giving his testimony and proclaiming the gospel, including that the crucified Christ rose from the dead. He was addressing King Agrippa II. It was at this point (v.24) that Festus, who had called on Agrippa for help in sorting out Paul’s case, interrupted him, accusing the Apostle of being “out of his mind.”

Paul addressed Festus’s accusation, adding that Agrippa understood what Paul was saying. Paul then appealed to Agrippa saying, “Do you you believe?” And then added, “I know you do.”

First, understanding and not thinking that believers are crazy is not the same as being “a believer” in Christ. We can be grateful when non-believers are not antagonistic regarding the gospel. We can rejoice if they listen, and even have a cursory understanding of the gospel. But we must not think that means they are actually believing Christians. Remember this when thinking about and/or talking to non-believers whom you know and wish were saved, but are not. This is not a matter of judging or condemning. But remembering this will keep us praying for their salvation.

Second, Paul’s words to Agrippa encourage us to be confident that even non-believers know that there is a God to whom all will one day answer (Romans 1:18-32). How do they know this even if they do not believe in Christ for salvation? Romans 1 makes it clear that God has placed this most basic knowledge in the conscience of every person. Though many (most?) non-believers “suppress this truth in unrighteousness” (Romans 1:18), they know in their heart of hearts that it is true. When people reject the gospel, we can appeal to their consciences like Paul did with Agrippa, to wrestle with the truth they know, but insist on denying.