I have seen and I testify that this is the Son of God.”
Again John bears witness and again uses the emphatic form of I saw which, along with the present form of “bare record” signifies that John was a witness to these facts and that they have a continuing effect upon him and upon what he has to say. His witness was not something he once said and has now forgotten; he does and will continue to tell what he knows.
John bears record that Jesus is the Son of God. He knows this because he heard God say it. (Luke 3:22)
Luke 3:22 and the Holy Spirit descended on him in bodily form like a dove. And a voice came from heaven: “You are my Son, whom I love; with you I am well pleased.”
Notice the use of the article “the.” Jesus is not just a son of God, He is the unique Son of God. This not only denotes the deity of Jesus, but displays the intimate relationship between Him and the Father; a further revelation of the intimacy revealed earlier between the Word (Logos) and the Father.