John was acquainted with the events that had marked the birth of Jesus. He had heard of the visit to Jerusalem in His boyhood, and of what had passed in the school of the rabbis. He knew of His sinless life, and believed Him to be the Messiah; but of this he had no positive assurance. The fact that Jesus had for so many years remained in obscurity, giving no special evidence of His mission, gave occasion for doubt as to whether He could be the Promised One. The Baptist, however, waited in faith, believing that in God's own time all would be made plain. It had been revealed to him that the Messiah would seek baptism at his hands, and that a sign of His divine character should then be given. Thus he would be enabled to present Him to the people. DA 109.3 When Jesus came to be baptized, John recognized in Him a purity of character that he had never before perceived in any man. The very atmosphere of His presence was holy and awe-inspiring. Among the multitudes that had gathered about him …
"And I knew him not: but that he should be made manifest to Israel, therefore am I come baptizing with water."
Both passages discuss John's initial lack of complete certainty about Jesus being the Messiah and the purpose of John's ministry being to reveal Jesus to Israel.