John the Baptist expected the coming of Yahweh

When John the Baptist saw Jesus coming to be baptized he was confused, because he expected Jesus to reveal himself as Yahweh. John expected Isaiah's prophecy:

Isaiah 35: 4 Tell those who have a troubled heart; take courage, and fear no longer; here is your God; vengeance will come, the retribution of God; he himself will come and deliver you. 5 Then the eyes of the blind will be opened, and the ears of the deaf will be open. 6 Then the lame will leap like a stag, and the tongue of the mute will sing in triumph; for waters will flow in the wilderness; and torrents, instead lonely.

He therefore did not understand why Jesus asked him to baptize him and he strongly rejected him, telling him that it was rather up to Jesus to baptize him:

Matthew 3:13 Then Jesus came from Galilee to the Jordan to John to be baptized by him. 14 But John kept him strong, saying, I need to be baptized by you, and you come to me? 15 And Jesus answering said unto him, Let [me] for the present: for thus it is convenient for us to fulfill all righteousness; and so he let him.

And just after that John will hear a voice from heaven saying concerning Jesus: this is my Son ...:

Matthew 3:16 And when Jesus was baptized, he immediately went out out of the water, and behold, the heavens were opened to him, and [John] saw the Spirit of God descending like a dove, and coming upon him. 17 And behold a voice from heaven, saying, This is my beloved Son, in whom I have delighted.

Jean was therefore confused; he didn't really understand what was going on because he thought Jesus was going to reveal himself to be Yahweh, but he obeyed without arguing. Some time later, John being in prison and close to being killed sent disciples to Jesus to ask him if it was really he who was to come or if they should wait for another. John expected the prophecy of Isaiah 35, so he asked Jesus if he was really the Yahweh who was to come or not:

Matthew 11: 2 Now John, hearing of the actions of Christ in the prison, sent two of his disciples to say to him: 3 Art thou the one who was to come, or whether we should expect another?

John was confused because Jesus was stripped of his identity and revealed himself not as Yahweh but rather as the Son of God and he was not yet baptizing with the Holy Spirit; because he had to do what is right first. And Jesus will answer him by telling the disciples of John to tell him what they saw and heard, namely the works mentioned in the prophecy of Isaiah 35:

Matthew 11: 4 And Jesus answering said unto them, Go, and tell John the things which ye hear and see. 5 The blind receive their sight, the lame walk, the lepers are cleansed, the deaf hear, the dead are raised, and the gospel is preached to the poor.

And Jesus knew that John would immediately understand that Jesus was giving him confirmation that he was indeed the Yahweh who was to come according to Isaiah and that he should not expect another, and he thus reassured John before his death.

John also expected the prophecy of Malachi 3 because he himself was the messenger who prepared the Way of Yahweh:

Matthew 11: 7 And as they were going, Jesus began to say of John to the troops: What did you go out to see in the wilderness? ....... 9 But what did you go to see? A prophet ? yea, I say unto you, and more than a Prophet.10 For he is he of whom it was [thus] written: Behold, I send my messenger before thy face, who shall prepare thy way before thee.

Malachi 3: 1 Behold, I send my messenger, and he will prepare the way before ME; and the Lord whom you seek will come suddenly to his temple, and the Angel of the covenant in whom you take pleasure, behold, he is coming, SAYS YAHWEH of hosts.

And he also expected the prophecy of Isaiah 40 because he was the voice of one crying in the wilderness:

Matthew 3: 1 Now at that time came John the Baptist, preaching in the wilderness of Judea; 2 And saying, Convert yourselves; for the kingdom of heaven is at hand. 3 For this is he of whom Isaiah the Prophet spoke, saying, The voice of him crying in the wilderness [is]: Prepare the way of the Lord, make his paths straight.

John 1:22 They said therefore unto him, Who art thou, that we may give an answer to those who sent us; what do you say about yourself 23 He said, I am the voice of one crying in the wilderness: Make straight the way of the Lord, as Isaiah the Prophet said.

Isaiah 40: 3 The voice of one crying in the wilderness [is]; prepare the way of the LORD; make up the paths for our God among the moors.