What does Luke 21:14 mean?

Between Jesus' ascension and His second coming, His followers will face hardships. The disciples are told very specifically to expect persecution: trials at the synagogues, imprisonment, and accusations before kings and governors. But this will happen for Jesus' sake. They will have the chance to speak about Jesus' resurrection in front of powerful authorities (Luke 21:12–13).

Ironically, they are not to prepare speeches for these trials. They are to let the Holy Spirit determine their words. He will tell them what to say so their logic is sound and their audience will recognize the truth (Luke 21:15). Whether the rulers accept the truth is a different issue.

That doesn't mean the disciples should be completely unprepared. The phrasing here is that they should not "meditate:" to prepare a speech or contrived script beforehand. Rather, they should trust that if they know their faith, and trust in their God, the rest will take care of itself. Jesus has spent three years with the Twelve as well as time with thousands of others who periodically followed Him. Peter, one of those Twelve, will say we are to be prepared to give a defense for the hope that is within us (1 Peter 3:15). It works. When Peter and John—two "uneducated, common men"—defend themselves before the Sanhedrin, the council members are "astonished" (Acts 4:13). They can't argue with their words or the miracle that gives evidence their words are from God. They can do nothing but threaten them (Acts 4:14–22).

Jesus' followers not only know the truth about Him, but they are also wise in the ways of the world. When Paul gives his defense before Agrippa, he is well-versed in the legal format of the defense he is expected to make (Acts 26:1–23). Governor Festus thinks Paul is out of his mind, but because Paul relies on the Holy Spirit to provide his words, King Agrippa knows Paul is telling the truth. He just doesn't want to accept it (Acts 26:24–29).