What does Luke 7:18 mean?

John the Baptist is in prison (Matthew 11:2) because he had publicly called out Herod Antipas for marrying his brother's wife (Luke 3:19–20). Antipas' territory includes two separate areas. Jesus is in Galilee, north of Samaria and west of the Sea of Galilee and the Jordan River. John is in Perea, farther south and east, on the other side of the Jordan and the Dead Sea from Judea.

Given that he was a prisoner, one might wonder how John heard what Jesus is doing. After Jesus raised the widow's son in Nain, "this report about him spread through the whole of Judea and all the surrounding country" (Luke 7:17). John knew his purpose was to identify Jesus as the Christ, and he made sure his disciples knew Jesus (John 1:35–36). Jews traveled from Galilee to Judea often to worship at the temple. If someone were in prison, his friends and family were responsible to feed him, so John's disciples would have seen him regularly. Paul's letters show that he had contact with friends even while in the Roman dungeons (2 Timothy 4:11–13).

John's disciples report Jesus' miracles, including healing the blind and raising the dead. The miracles Jesus is doing, particularly raising the widow's son (Luke 7:14–15), healing the centurion's servant (Luke 7:1–10), and other miracles the men witness directly (Luke 7:21) prove Jesus is at least a great prophet. The question is, is He the Messiah: the Promised Savior?