John 1:6-11 There was a man sent from God, whose name was John. The same came for a witness, to bear witness of the Light, that all men through him might believe. He was not that Light, but was sent to bear witness of that Light. That was the true Light, which light every man that come into the world. He was in the world, and the world was made by him, and the world knew him not. He came unto his own, and his own received him not.
This John refers to John the Baptist, used 20 times in this gospel and never by the title ‘Baptist’ as in the other gospels; he is not to be confused with John the Apostle who is the author of this gospel as well as 1,2,3 John and Revelation. John the Baptist was not the light but came to witness of the Light – the true Light that is Jesus Christ the Messiah (John 8:12; 9:5; 12:35-46) so that men can believe through Him (John 14:6) and be reconciled with the Father.
Jesus Christ became flesh – He came into the world – the same world (earth) He created (Col. 1:15-17) and they (people) knew Him not – most people chose not to have a relationship with God and when Christ came, He did not come as they would have preferred: as a king and to set them free from earthy rulers, but instead He came as a pauper and came to free us of sin, so the people rejected Him. Even His own nation, the Jews (or Israel) through whom He could demonstrate to other nations what God purposed for mankind.