Why were the disciples so bold after the resurrection?
The disciples were bold because the resurrection gave them proof and power that removed fear. Before, they had scattered in fear, but afterward nothing could shake them. Rome and the Jews did not scare them. They knew death was only temporary because of resurrection power.
Les explains that the disciples' boldness after the resurrection was rooted in the proof of the resurrection. Peter, who at the night of the arrest and conviction betrayed Him, swore with an oath that he did not know Him, and the others scattered in fear for their lives, became a standing evidence of resurrection. Afterward the disciples had a boldness no one could shake. Rome did not scare them, the Jews did not scare them; resurrection power and the proof of it did. Les applies this to believers who might face pressure or persecution, saying they should be so bound in the hope and power of resurrection that they are not afraid of what can be done to this body of flesh, because death is only temporary because of resurrection power.