In response to Jesus’ statement that he was the light of the world, the Pharisees argued that he had no right to testify on his own behalf. In their view he had no supporting witnesses (John 8:12-13). Jesus replied that he did have the right to bear witness to himself, because he came from God and was united with God. God was his supporting witness, and that should have been sufficient (John 8:14).
The Jews were wrong in their judgments against Jesus, because they judged in a totally human way.
The time for Jesus to act as the world’s judge had not yet come, but even if he carried out such work immediately, his judgment would be true, again because of the unity between the Father and the Son (John 8:15-16). If the Jews insisted on having two witnesses as the law required, they had them in the Father and the Son. The two were in agreement, and therefore the Jews had to accept their testimony (John 8:17-18). The reason that Jesus’ opponents failed to grasp what he was saying was that they did not know God (John 8:19-20).