Note: The following is a translation from an entry for a small reference work that we hope to publish in Brazil. It is tentatively called Pequena referência bíblica.
With one word, God created light, Genesis 1.3; Hebrews 11.3. He also created lights in the sky: sun, moon and stars “to mark seasons, days, and years” Genesis 1.14ff. He is therefore the “Father of lights” James 1.17. With other lights there are variations and shadows, but not with God.
“God is light” 1John 1.5. He is true and holy. His nature determines the conduct of his children, 1 John 1.6-7. It is necessary to walk in the light, that is, to conduct oneself according to the divine character, or obey the truth, 1 John 1.8; John 3.21.
Light reveals and makes things visible, so God is also light in this sense: he reveals himself, his nature, his work, his plan, his truth, and his demands. The Psalmist prayed: “Reveal your light and your faithfulness. They will lead me; they will escort me back to your holy hill, and to the place where you live” Psalm 43.3.
As God is a light to his children on earth, he is also a light in the eternal heaven, Revelation 22.5.
The light of Christians represents their mission in the world, Matthew 5.16; Philippians 2.15; Ephesians 5.8. The disciples are called “sons of light” Lucas 16.8; John 12:36; Ephesians 5.8; 1 Thessalonians 5.5, for they “share in the saints’ inheritance in the light” Colossians 1.12.
The call that goes out to all people everywhere is to allow oneself to be reached by the light of Christ: “Awake, O sleeper! Rise from the dead, and Christ will shine on you!” Ephesians 5.14.