What does John 9:38 mean?

This moment is similar to how Thomas will respond to his encounter with a resurrected Jesus later in this gospel (John 20:24–29). Prior to this moment, all the once-blind man knew is that he had been healed by "a prophet" from God (John 9:6–7, 11). When that healer—Jesus—found the man, he admitted that he did not know who the Son of Man was, but wanted to know so he could respond in faith. Hearing that this Messiah was Jesus, the man immediately responded with worship.

The religious leaders of Jerusalem respond to Jesus in exactly the opposite way. This man accepts the evidence he has, rather than looking for excuses about what he does not know (John 9:25). He seeks to follow God faithfully, but admits his own ignorance (John 9:36). The scribes and Pharisees don't want to understand the truth (John 7:17), and they reject all the knowledge they already have (John 5:39–40).

This moment is also important when discussing Jesus' claims to be God. In other portions of Scripture, worship of any being other than God is forbidden (Exodus 20:3–4). When someone mistakenly worships other beings, such as angels, those beings respond by refusing that worship (Revelation 19:9–10). As with Thomas, Jesus accepts the worship of this newly-seeing man. By implication, Jesus is agreeing that He can be worshipped, which from a Jewish perspective means He is claiming to be identical to God.