In the Bible, light indicates what is good, pure, and holy. Darkness is synonymous with sin and evil. To say that God is light is to assert that God is perfectly pure and holy. Only God is without sin. He is the standard of perfection and truth by which everything is measured.
Light reveals. Light shows the true nature of things. When confronted by God, people become painfully aware of their own failures and sin. God’s “light” brings this painful crisis, then liberates us into true freedom and joy. Like a brilliant spotlight, God guides His creatures out of the dangerous darkness of their sinful lives into a place of safety and peace. Darkness and light cannot coexist (1 John 1:5-6). To know God, we must put aside sin.
1 JOHN 1:5 – 5 This then is the message which we have heard of him, and declare unto you, that God is light, and in him is no darkness at all.