What does John 5:30 mean?
In John 5:16–29, Jesus begins to respond to His critics. These men are persecuting Him, even attempting to kill Him, for breaking Sabbath traditions and claiming to be equal to God (John 5:18). Verse 30 summarizes the point Jesus made in the prior passage: He is in perfect unity with God the Father. In those verses, Jesus claimed to have many of the attributes of God. In particular, Jesus stated that His works (John 5:19), love (John 5:20), power over life and death (John 5:21), judgment (John 5:22), and honor (John 5:23) were identical to those of God.This verse provides a bridge from Jesus' claims about His unity with God into the evidence which supports these claims. Jesus is justifying His teaching, and His ministry, by connecting it to the will of God.
There are some things which only Jesus can speak of, because only He could possibly know them (John 8:14). However, in this context, He is discussing truths which other people can verify. So, they fall under the normal view of Jewish law, where a person could not testify on their own behalf. Rather, two or three witnesses were needed to consider something reliable (Deuteronomy 17:6; Numbers 35:30). As the upcoming verses will show, Jesus does not appeal to "blind faith," or naked trust, when He is challenged. On the contrary, Jesus will acknowledge the need for evidence (John 5:31, 34), and then provide examples which prove His claims.