Hi Jingle,
John the Baptist was a Jew, and in that first century their idea of the coming Messiah was a conquering Savior, one who would free them from Roman control.
Isa 9:6 For unto us a Child is born, Unto us a Son is given; And the government will be upon His shoulder. And His name will be called Wonderful, Counselor, Mighty God, Everlasting Father, Prince of Peace.
v. 7 Of the increase of His government and peace There will be no end, Upon the throne of David and over His kingdom, To order it and establish it with judgment and justice From that time forward, even forever. The zeal of the Lord of hosts will perform this.
Jesus' mission had nothing to do with gaining Judea's independence, but John was not ignorant of these prophecies. But as you said, John had seen the Spirit of God descending on Jesus at His baptism, heard a voice from heaven, declaring Him the Son of God (John 1:34). John often pointed Jesus out to others, and declared Him the Lamb of God (John 1:29,36) and bridegroom (John 3:29).
John 1:29 The next day John saw Jesus coming toward him, and said, "Behold! The Lamb of God who takes away the sin of the world!
Luke 3:21 When all the people were baptized, it came to pass that Jesus also was baptized; and while He prayed, the heaven was opened.
v. 22 And the Holy Spirit descended in bodily form like a dove upon Him, and a voice came from heaven which said, "You are My beloved Son; in You I am well pleased."
But was John confused, as the disciples were as to Jesus' humble attitude, instead of a powerful conqueror?
Luke 19:11 Now as they heard these things, He spoke another parable, because He was near Jerusalem and because they thought the kingdom of God would appear immediately.
In prison did John have doubts and wondered why Christ did not deliver him? OR did John expect to be executed and want his disciples to see firsthand that Jesus was the Messiah and believe in Him and therefore sent his disciples to ask a few questions of Jesus for 'their' assurance? Early on Andrew was John's disciple and went to follow Jesus (John 1:35-40), maybe these were reluctant to embrace another. So whatever it was it does seem more likely to me that it was for his disciples sake.
Mat 11:2 And when John had heard in prison about the works of Christ, he sent two of his disciples
v. 3 and said to Him, "Are You the Coming One, or do we look for another?"
v. 4 Jesus answered and said to them, "Go and tell John the things which you hear and see:
v. 5 The blind see and the lame walk; the lepers are cleansed and the deaf hear; the dead are raised up and the poor have the gospel preached to them.
v. 6 And blessed is he who is not offended because of Me."
mercy, peace and love
Kat