John 3:19

This is the judgment (that is, the cause for indictment, the test by which people are judged, the basis for the sentence); the Light has come into the world, and people loved darkness rather than the Light, for their deeds were evil.

People will reject the light when they see their wisdom as more significant than God’s. They become an all-knowing judge for themselves, and the judgment of sin disappears. They have rejected God. God’s word transforms the heart, opens the eyes to sin, and keeps believers from falling away from God. The light of God is safety and salvation.