Why is God described as light?

The description of God as Light captures the essence of His nature and is foundational to the rest of the epistle. However, unlike the straightforward expressions “God is spirit” (meaning that God is immaterial in form; compare John 4:24 with Luke 24:39) and “God is love” (meaning that the persons of the Trinity love one another and mankind; cf. 3:17; 4:7, 16; Mic. 7:18; Zeph. 3:17; John 5:42; 15:10; Rom. 5:5, 8; 8:39; Eph. 2:4; Titus 3:4), the idea that God is Light (cf. Ps. 78:14; Isa. 60:19–20; John 1:9; 3:19; 8:12; 9:5; 12:46; Acts 9:3; Rev. 21:23) is more complex.

Throughout the Scriptures, God and His glory are often described in terms of light. For example, during the exodus God appeared to the Israelites in the form of light:

    The Lord was going before them in a pillar of cloud by day to lead them on the way, and in a pillar of fire by night to give them light, that they might travel by day and by night. He did not take away the pillar of cloud by day, nor the pillar of fire by night, from before the people. (Ex. 13:21–22; cf. 40:34–38; 1 Kings 8:11)

When Moses came down from Mount Sinai after meeting with the Lord, his face glowed with a reflection of God’s light (Ex. 34:29–35; cf. 2 Cor. 3:7–8). In Psalm 104:1–2, the psalmist says, “Bless the Lord, O my soul! O Lord my God, You are very great; You are clothed with splendor and majesty, covering Yourself with light as with a cloak, stretching out heaven like a tent curtain” (cf. 1 Tim. 6:14–16). Not only is God light in His essence, but He also is the source of the believer’s light (Ps. 27:1; John 1:9; 12:36).
At the transfiguration, when Jesus gave the three apostles a glimpse of His full glory, He manifested Himself as light: “He was transfigured before them; and His face shone like the sun, and His garments became as white as light” (Matt. 17:2). Second Corinthians 4:4–6 summarizes well the importance of God as light and its role in a Christian’s life:

    The god of this world has blinded the minds of the unbelieving so that they might not see the light of the gospel of the glory of Christ, who is the image of God. For we do not preach ourselves but Christ Jesus as Lord, and ourselves as your bond-servants for Jesus’ sake. For God, who said, “Light shall shine out of darkness,” is the One who has shone in our hearts to give the Light of the knowledge of the glory of God in the face of Christ. (cf. Matt. 5:14–16; Eph. 5:8–10; Phil. 2:15; Col. 1:12–13; 1 Peter 2:9)

Although the foregoing passages describe the significance of divine light, they do not define it. However, Psalm 36:9 does: “For with You is the fountain of life; in Your light we see light” (cf. 1 Peter 2:9). Here the psalmist employed a Hebrew parallelism, using two statements to say the same thing. He equates light and life—God is light in the sense that He is life, and He is the source and sustainer of both physical and spiritual life.

John expressed that truth in the prologue to his gospel:

 In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God. All things came into being through Him, and apart from Him nothing came into being that has come into being. In Him was life, and the life was the Light of men. The Light shines in the darkness, and the darkness did not comprehend it. There came a man sent from God, whose name was John. He came as a witness, to testify about the Light, so that all might believe through him. He was not the Light, but he came to testify about the Light. There was the true Light which, coming into the world, enlightens every man. He was in the world, and the world was made through Him, and the world did not know Him. He came to His own, and those who were His own did not receive Him. But as many as received Him, to them He gave the right to become children of God, even to those who believe in His name, who were born, not of blood nor of the will of the flesh nor of the will of man, but of God. (John 1:1–13; cf. 2:23–3:21; Col. 1:15–17)

“I am the Light of the world,” Jesus declared; “he who follows Me will not walk in darkness, but will have the Light of life” (John 8:12; cf. 12:45–46). God, the source of true light, bestows it on believers in the form of eternal life through His Son, who was the light incarnate.

Scripture reveals two fundamental principles that flow from the foundational truth that God is light. First, light represents the truth of God, as embodied in His Word. The psalmist wrote these familiar words: “Your word is a lamp to my feet and a light to my path.… The unfolding of Your words gives light; it gives understanding to the simple” (Ps. 119:105, 130; cf. Prov. 6:23; 2 Peter 1:19). The light and life of God are inherently connected to and characterized by truth.
Second, Scripture also links light with virtue and moral conduct. The apostle Paul instructed the Ephesians, “You were formerly darkness, but now you are Light in the Lord; walk as children of Light (for the fruit of the Light consists in all goodness and righteousness and truth)” (Eph. 5:8–9; cf. Isa. 5:20; Rom. 13:12; 1 Thess. 5:5–6).

Those two essential properties of divine light and life are crucial in distinguishing genuine faith from a counterfeit claim. If one professes to possess the Light and to dwell in it—to have received eternal life—he will show evidence of spiritual life by his devotion both to truth and to righteousness, as John writes later in this letter:

The one who says he is in the Light and yet hates his brother is in the darkness until now. The one who loves his brother abides in the Light and there is no cause for stumbling in him. But the one who hates his brother is in the darkness and walks in the darkness, and does not know where he is going because the darkness has blinded his eyes. (2:9–11; cf. Matt. 5:16; 25:34–40; Luke 1:6; 11:28; Rom. 6:17; 16:19; Phil. 1:11; Titus 2:7; James 2:14–20)

If truth and righteousness are absent from one’s life, that person, no matter what he or she says, does not possess eternal life (Matt. 7:17–18, 21–23; 25:41–46). They cannot belong to God, because in Him there is no darkness at all. God is absolutely perfect in truth and holiness (Ex. 15:11; 1 Sam. 2:2; Pss. 22:3; 48:10; 71:19; 98:2; Isa. 6:3; Rev. 4:8; 15:4). Obviously, believers fall far short of that perfection, but they manifest a godlike desire for and continual striving toward heavenly truth and righteousness (cf. Phil. 3:7–16).


MacArthur, J. (2007). 1, 2, 3 John (pp. 23–25). Chicago, IL: Moody Publishers.