“And it happened when Jesus finished commanding His twelve disciples, He left there to teach and to proclaim in their cities. But hearing in the prison of the works of Christ, sending two of his disciples, John said to Him, Are You the [One] coming, or are we to look for another? And answering, Jesus said to them, Going, relate to John what you hear and see: The blind receive sight, and the lame walk; lepers are cleansed, and the deaf hear; the dead are raised, and the poor are given the gospel. And blessed is the [one,] whoever shall not be offended in Me. But as these were going, Jesus began to say to the crowds about John, What did you go out into the wilderness to behold? A reed being shaken with the wind? But what did you go out to see? A man being clothed in soft garments? Behold, those wearing soft things are in the houses of kings. But what did you go out to see? A prophet? Yes, I say to you, and [one] more excellent than a prophet. For this is [the one] about whom it has been written: Behold, I send out My messenger before Your face, who shall prepare Your way before You. Truly I say to you, [There] has not arisen among [those] born of a woman [any] greater than John the Baptist. But the least in the kingdom of Heaven is greater than he is. But from the days of John the Baptist until now, the kingdom of Heaven suffers violence, and [the] violent seize it. For all the Prophets and the Law prophesied until John. And if you are willing to receive, he is Elijah, the [one] going to come. The [one] having ears to hear, let him hear” (Matthew 11:1-15; cf. Luke 7:18-28).
There are certain self-righteous religionists who will wrest and adulterate this Scripture by claiming that while in prison John the Baptist had doubts about who he was about. One such self-righteous religionist is Jon Bloom who (associated with “desiring god ministries”). On February 13, 2009  Bloom wrote an article called “John the Baptist’s Doubt.” Several years ago I responded here to Jon Bloom’s slanderous, pseudo-pious, and pseudo-humble dung.
 I noticed just today that this dung was re-posted on November 9, 2012.
Not too long ago I was listening to a sermon by the influential heretic John Piper, where he said something like (my paraphrase of Piper) ‘that’s why John the Baptist got so muddled.’ I forget the precise context, and I’m not sure “muddled” was the exact word Piper used, but it was quite clear that Piper was expressing the same idea as Jon Bloom concerning John the Baptist.
I did read a few other Calvinist-Reformed commentators and they concluded basically the same idea as Thomas Watson does here (this is NOT an endorsement or promotion of Watson as a true Christian):
“John the Baptist, hearing in prison of the fame of Christ, sends two of his disciples to Him with this question, ‘Art Thou He that should come, or do we look for another?’ (Matt. 11:3). Not (as Tertullian thinks) that John the Baptist knew not that Jesus Christ was the true Messiah, for he was confirmed in this both by the Spirit of God and by a sign from heaven (John 1:33). But John the Baptist hereby endeavored to correct the ignorance of his own disciples who had a greater respect for him than for Christ.
In the fourth verse Christ answers their question, ‘Go back and shew John again those things which ye do hear and see: the blind receive their sight, and the lame walk, the lepers are cleansed,’ etc. Jesus Christ demonstrates Himself to be the true Messiah by His miracles which were real and occular [sic] proofs of His divinity. John’s disciples being departed, Christ falls into a high praise and commendation of John the Baptist, ‘What went ye out into the wilderness to see? A reed shaken with the wind?’ (Matt. 11:7). As if Christ had said, John the Baptist was no unconstant [sic] man, fluctuating in his mind and being shaken as a reed from one opinion to another; he was no Reuben, unstable as water, but was fixed and resolute in religion, and a prison could make no alteration in him. ‘But what went ye out for to see’? A man clothed in soft raiment?’ (Matt. 11:8). John did not indulge his senses; he wore not silks, but camel’s hair; nor did he affect to live at court, but in a wilderness (Matt. 3:3,4).
Again, Christ commends John as being His forerunner who prepared the way before him (Matt. 11:10). He was the morning star which did precede the Sun of Righteousness; and that Christ might sufficiently honor this holy man, He does not only parallel him with, but prefers him before, the chief of the prophets…He was eminent both for dignity of office and perspicuity of doctrine” (Thomas Watson, Heaven Taken by Storm, pp. 1-2).
So, according to Thomas Watson Tertullian thought that John the Baptist “knew not that Jesus Christ was the true Messiah.” Bloom’s basic idea was that while inside the prison cell, John the Baptist experienced some kind of intense ambivalence concerning whether or not he was a true prophet, or whether or not he had been pointing others to a false Messiah — quite repulsive.
Bloom and Piper basically think John the Baptist was an unstable and irresolute reed. Jesus Christ CONTRADICTS Bloom and Piper by saying that John the Baptist was NOT a reed shaken by the wind. He was the fixed and resolute forerunner of the God-Man Mediator, Jesus Christ.
“And an angel [of the] Lord appeared to him, standing on [the] right of the altar of incense. And seeing [this], Zacharias was troubled, and fear fell on him. But the angel said to him, Do not fear, Zacharias, because your prayer was heard, and your wife Elizabeth will bear a son to you, and you shall call his name John. And he will be joy and exultation to you, and many will rejoice over his birth. For he shall be great in the eyes of the Lord, and he shall not drink wine or strong drink. And he will be filled of [the] Holy Spirit, even from his mother’s womb. And he will turn many of the sons of Israel to [the] Lord their God. And he will go out before Him in [the] spirit and power of Elijah to turn [the] hearts of fathers to [their] children, and disobedient ones to [the] wisdom of [the] just, to make ready a people having been prepared for [the] Lord” (Luke 1:11-17).
“And this is the witness of John, when the Jews sent priests and Levites that they might ask him, Who are you? And he acknowledged and did not deny; yea, [he] acknowledged, I am not the Christ. And they asked him, What, then? Are you Elijah? And he said, I am not. Are you the Prophet? And he answered, No. Then they said to him, Who are you, that we may give an answer to those sending us? What do you say about yourself? He said, I [am] a voice crying in the wilderness: Make straight the way of the Lord, as Isaiah the prophet said. And those who had been sent were of the Pharisees. And they asked him and said to him, Why then do you baptize, if you are not the Christ, nor Elijah, nor the Prophet? John answered them, saying, I baptize in water, but [One] stands in your midst whom you do not know; This One it is who has come after me, who has been before me, of whom I am not worthy that I should loose the thong of His sandal. These things took place in Bethabara beyond the Jordan, where John was baptizing. On the morrow, John sees Jesus coming toward him and said, Behold! The Lamb of God, taking away the sin of the world!” (John 1:19-29)