“You Yourselves bear me witness that I said ‘I am not the Christ, but I have been sent before Him’.” (John 3:28)
Of course John’s comment is in light of his ministry. For he says that he was to announce the Christ because he is not the Christ: his role was to prepare the way. John sees that his own life isn’t purposeless but is actually tied up in the work of God by the presentation of the Lamb of God.
He was sent to preach repentance and when he saw the Lamb of God he pointed him out, openly acknowledging that this is the provision that God had made. (John 1:19-34)
To John’s mind, this probably meant something else. He probably thought as Jesus as the Lamb ruler who would forcefully take away the sins of the World. After all, it was only a short time later that he would be imprisoned, still waiting for the Christ to reboot this entire world, and wondering why it hadn’t happened yet.
In Matthew 11, John, seeing that Herod is still in power (and he’s still in jail) sends a message to Jesus via disciples: “Are you the Christ that we’re waiting for?” He spent his life pointing out this person, he could’ve sworn that this was the very thing he was called to do, but things had turned out so differently and dire: could he have been wrong?
Christ responds neither yes nor no but pointing out the work of God. The Lame walk. The blind see. The Gospel is being preached.
You see, Christ explains, John wasn’t merely some spectacle in soft clothes out in the wild—some oddity to ogle. This John was God’s prophet: the very Elijah who was supposed to come (if they would have had him) before the end of the age: the one who prepared the way of the coming of the Lord Himself. This John, in prison who eventually died of beheading, was the greatest of the prophets (Matt 11:11a).
Without a miracle. Without a sign. With a backwater ministry in the Jewish outback. John functioned where he was supposed to function doing what all the prophets before him did, but better. Point to Christ.
Every single prophet in the Old Testament pointed forward to Christ via the power of the Holy Spirit. Sometimes fuzzily. Sometimes explicitly. But always predicated upon God’s revelation and looking forward to God’s distant promises. John alone, out of all the prophets, announced Him within days, inaugurated him via baptism, and witnessed the descending Holy Spirit upon Him. None of the prophets were given that position (Heb 11:39).
But John didn’t see everything. He was still an Old Testament prophet. He didn’t see the crowds cheering around the one who comes in the name of the Lord (Mark 11:9; John 12). To him wasn’t given the horror of seeing the Messiah rejected and pinned to a tree (John 19). He would never witness the wonder of the risen Messiah (John 20). To him wasn’t given the chance of listening to the risen Lord for several days before he was taken up into heaven (Acts 1). To him wasn’t given the chance of participating in the prophesying in tongues which was a witness of the Holy Spirit being poured out in the last days (Acts 2).
None of those things were given to him; God didn’t grant John that role.
And he knew that at this point.