“God is light,” says 1 John 1:5. Light is a common metaphor in the Bible. Proverbs 4:18 symbolizes righteousness as the “morning sun.” Philippians 2:15 likens God’s children who are “blameless and pure” to shining stars in the sky. Jesus used light as a picture of good works: “Let your light shine before others, that they may see your good deeds” (Matthew 5:16). Psalm 76:4 says of God, “You are radiant with light.”
The fact that God is light sets up a natural contrast with darkness. If light is a metaphor for righteousness and goodness, then darkness signifies evil and sin. First John 1:6 says that “if we claim to have fellowship with him and yet walk in the darkness, we lie and do not live out the truth.” Verse 5 says, “God is light; in him there is no darkness at all.” Note that we are not told that God is a light but that He is light. Light is part of His essence, as is love (1 John 4:8).The message is that God is completely, unreservedly, absolutely holy, with no admixture of sin, no taint of iniquity, and no hint of injustice.