John 1:6-9

There came a man who was sent from God; his name was John. He came as a witness to testify concerning that light, so that through him all men might believe. He himself was not the light; he came only as a witness to the light. The true light that gives light to every man was coming into the world.

his name was John
Matthew 3:1 In those days John the Baptist came, preaching in the Desert of Judea ...

he came as a witness to testify
John 1:15 John testifies concerning him. He cries out saying, "This was he of whom I said, 'He who comes after me has surpassed me because he was before me.'"
John 1:19 Now this was John's testimony when the Jews of Jerusalem sent priests and Levites to ask him who he was.
John 1:32 Then John gave this testimony: "I saw the Spirit come down from heaven as a dove and remain on him."
John 3:26 They came to John and said to him, "Rabbi, that man who was with you on the other side of the Jordan--the one you testified about--well, he is baptizing, and everyone is going to him."
John 5:33 "You have sent to John and he has testified to the truth."

so that through him all men might believe
John 1:12 Yet to all who received him, to those who believed in his name, he gave the right to become children of God--
John 3:15 "... that everyone who believes in him may have eternal life."

The true light
1 John 2:8 Yet I am writing you a new command; its truth is seen in him and you, because the darkness is passing and the true light is already shining.

that gives light to every man
Isaiah 49:6 ... he (the LORD) says: "It is too small a thing for you to be my servant to restore the tribes of Jacob and bring back those of Israel I have kept. I will also make you a light to the Gentiles, that you may bring my salvation to the ends of the earth."

NOTES:
John 10:41; 20:31

(parentheses are mine)

Scriptures taken from the Holy Bible, New International Version® NIV®, Copyright© 1973, 1978, 1984 by International Bible Society. Used by permission. All rights reserved worldwide.