We have to be careful with this? There is a primary promise to the apostles, inspired men, but secondarily there is a promise to us also to a lesser extent. In the case of the apostles, they would literally be given the words to speak.
We have a modern equivalent to that of the apostles in being told to keep their defence spiritual. There is a wrong response, a response which is too intellectual. Some resort to complex apologetics. Outside of the context of persecution, the strategy they adopt to secularism is to go and penetrate and enter the world of cynics, and play them at their own game. But Christ’s principle is: stay with the spiritual. Focus on the truth. Don’t be drawn aside. Don’t follow the normal line of defence.
The lesson is that God will not desert his people in their hour of need. He will not desert them just when they are doing their most important work for him. We must not be anxious in such a situation. That might seem natural when speaking before such elevated ones in this world, but their elevation is only for a short time. God is content to speak to them through us! What a high privilege we have, especially when we are called to suffer persecution for his sake.