6 There was a man sent from God, whose name was John.
7 The same came for a witness, to bear witness of the Light, that all men through him might believe.
8 He was not that Light, but was sent to bear witness of that Light.
Prophecies about John:
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 (Isaiah 49:3)
Behold, I will send my messenger, and he shall prepare the way before Me: and the LORD, whom ye seek, shall suddenly come to His temple, even the messenger of the covenant, whom ye delight in: behold, He shall come, saith the LORD of hosts (Malachi 3:1).
John is referred to as a light — candle — in John 5:35 — He was a burning and a shining light: and ye were willing for a season to rejoice in his light.
Light (referring to Christ) = the light, the source of light
through him (verse 7) — John as a witness
Christ cast light on every man to show the contrast between them and Him, and their need for Him.
John = the gift from God, or, God is gracious.
When light is shining, only the blind have to be told.
There is a striking contrast between the ministry of John as recorded by Matthew and the witness he bore of the Light as in John. These two contrasting messages of John can be understood only as it is remembered that he was the forerunner of One Who Himself had a two-fold ministry, (1) to the circumcision (Jews) to confirm the promises made to the fathers and (2) that the Gentiles might glorify God [through Israel] for His mercy (Romans 15:8-9). Space will not permit a detailed comparison of these two messages by John but suffice it to say that in Matthew his message is one of wrath and judgment and a call to bring forth “fruits meet for repentance” (Matthew 3:1-12). This is the message of the law [as is fitting in a book the presents Christ as King of the Jews].
In the Gospel of John it is entirely different; “Of His fulness have we all received, and grace for grace” (v. 16). Here is no call to do; it is a message concerning a gift of the fulness of the Word and grace upon grace. He was not only Himself “full of grace and truth” but of that same “fulness have we all received” not only grace but “grace upon grace.” [as is fitting in a book that presents Christ as the Son of God] — Strombeck, page 20-21.