What does Luke 11:34 mean?
Jesus continues His admonition to the scribes and Pharisees: to share the truth they know. He has shown the light of who He is (Luke 11:29–33). The reality that He is Messiah was evident. Yet the religious leaders' hearts are darkened. Even though they have proof that Jesus is the Jewish Messiah, they refuse to admit it. Rather than believe and seek further understanding, they accuse Jesus and demand signs (Luke 11:14–16). If their eyes—their perception of what is real—were clear, the light of truth would enter their hearts. But their perceptions are bad, and so their hearts are filled with darkness. They don't believe, so they're blind to truth; blindness to truth prevents them from believing (John 5:39–40; 7:17).For Jesus' audience, the "light" they should be seeing is how Christ fulfills Messianic prophecies from the Old Testament. Especially important are predictions that the Messiah would bring sight to the blind, hearing to the deaf, and speech to the mute (Isaiah 35:5–6; Luke 11:14).
Evidence for those of us in the modern world is a bit different since we can't see Jesus' miracles first-hand. We can know that God is the powerful and divine Creator by looking at creation (Psalm 19:1; Romans 1:19–20). We can read the Bible and realize that it accurately describes our fallen world. We can recognize that real goodness must be grounded in something outside of us. As we affirm each truth, we take a step forward in faith, trusting that what the Bible says about Jesus must be true. But if we succumb to pride, hurt from wounds, or rebellion against God's expectations for our behavior, that darkness blinds us to the truth of who Jesus is.
If, however, we read something in Scripture we know to be true, then build on that truth by having faith that Scripture is true in other areas, we will reach the realization that Jesus is not just the Jewish Messiah. He is God and the Son of God who came to earth in human form, died to take the penalty for our sins, and rose on the third day. And that truth will shine out of us as evidence to others of God's truth.