John 1

The Jews looked forward to the comingof the Messiah and were more than familiar with the prophecy of Isaih of -

"The voice of him that crieth in the wilderness, Prepare ye the way of the LORD, make straight in the desert a highway for our God." (Old Testament | Isaiah 40:3)

As well as the prophecies of Malachi -

"...I will send my messenger, and he shall prepare the way before me...
(Old Testament | Malachi 3:1)

The scribes and Pharisees were also aware of these prophecies so when they heard of one that professed to be a prophet, they sent priests and levites to inquire of John the Baptist -

"...Who art thou?
20 And he confessed, and denied not; but confessed, I am not the Christ.
21 And they asked him, What then? Art thou Elias? And he saith, I am not. Art thou that prophet? And he answered, No." (New Testament | John 1:19 - 21)

So again they asked him -

"Who art thou? that we may give an answer to them that sent us. What sayest thou of thyself?" (New Testament | John 1:22)

With all the understanding of his foreordained mission, John the Baptist declared -

"I am the voice of one crying in the wilderness, Make straight the way of the Lord, as said the prophet Esaias." (New Testament | John 1:23)

John's mission was to do just that, to not only prepare the way but to be the one that was to testify that Jesus was the Son of God. And thus he wrote -

"...I saw, and bare record that this is the Son of God..." (New Testament | John 1:34)

John was to preach and teach as a prophet of God to bring many to believe and then declaring to those that had believed and followed him of the Savior -

"Behold the Lamb of God!" (New Testament | John 1:36)