What does John 5:39 mean?

Verses 39 and 40 summarize a crucial point about the difference between faith and belief. A person who refuses to believe cannot be convinced, no matter what evidence they are given (John 5:40). In verses 37 and 38, Jesus criticized the local religious leaders for never hearing the voice of God. They are rejecting Jesus and His message (John 5:18) because they are unwilling, not because they are uninformed.

This is a key idea to consider when discussing ideas such as evidence, proof, and faith. The Bible never calls on anyone to express "blind faith," which is belief without evidence. In this very passage, Jesus is responding to criticism by giving three separate forms of evidence. He has mentioned human testimony (John 5:33) and direct observation—in the form of His miracles (John 5:36). Now, He is referring to the evidence of God's written Scripture. And yet, for some, this is not enough and never will be.

This is why God does not offer "proof" to all people: it won't necessarily produce obedience or trust. Simply knowing that God exists does not mean obedience will follow (James 2:19). Having knowledge does not always mean trusting in God, as Israel's own disobedience showed (Numbers 14:20–23; Nehemiah 9:16–17; Psalm 78:11–12). And, here, the fact that the Pharisees were knowledgeable in the Scriptures did not necessarily mean they were willing to accept Jesus (John 7:17).

Verse 40 will show the real problem behind the disbelief of these religious hypocrites, which is also the basic problem with all who reject Jesus Christ: they do not believe because they will not believe. No amount of proof is enough to overcome that.