1. Troubled disciples of John (18-20)
John the Baptist had called the people of his time to repent, and had even challenged King Herod's immoral life. His good works prepared the way for the Lord's coming. But now he was in prison and soon to be killed. Doubt began to attack John's disciples and possibly John himself, so he sent two of his disciples to ask Jesus if he was really the one they were hoping for. This is the best thing to do when doubts arise.
2. "Go back and report" (21-23)
In response, Jesus simply described his messianic ministry using the words of the prophet Isaiah. (Isa 61:1; 35:5,6) Jesus' ministry fit God's word, verifying God's faithfulness and Jesus' identity. God doesn't promise an easy life, but a meaningful life. Jesus taught John's disciples to focus on the work of God that was going on, and gave a victorious report for them to bring back to John in prison.