He came as a witness to testify concerning that light, so that through him all men might believe. He came as a witness to testify concerning that light, so that through him all men might believe. And so we are introduced to John the Baptist, one of the most important people in the Bible. In contrast, here we have John the Baptist who was a man. And indeed, John was a gift of God to the world, preparing the way for Jesus Christ, heralding the coming of our Lord and King.
Light only needs a witness to a blind person.
Our moral blindness has made it necessary for the light to need testimony. This description of John the Baptist could very well be applied to all ministers of the Gospel, and we should all strive so that it may be applied to us. They should not enter the ministry because of their own worldly ambitions, but because of God's call on their lives. Christ should be the central theme of every sermon and Bible study. God chooses to do His work primarily through men.