"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." (1 John 1:5)
Light is the most fundamental and important form of energy, and energy includes every phenomenon in the physical universe. It is appropriate for John to affirm that God is light, because everything created must reflect the character of its Creator. The term "light," therefore, has come to be applied not only to light in the physical sense, but also to that which is true in the intellectual realm, and holy in the moral realm as well.
In terms of truth and genuine knowledge, "the entrance of thy words giveth light" (Psalm 119:130). "In thy light shall we see light" (Psalm 36:9). Without God's truth, there is only darkness. "The god of this world hath blinded the minds of them which believe not, lest the light of the glorious gospel of Christ, who is the image of God, should shine unto them" (2 Corinthians 4:4). The Bible also speaks of light as moral holiness. "For ye were sometimes darkness, but now are ye light in the Lord: walk as children of light. . . . And have no fellowship with the unfruitful works of darkness, but rather reprove them" (Ephesians 5:8, 11).
There are still other analogies: "In him was life; and the life was the light of men" (John 1:4). Not only is light symbolic of life itself, but it also depicts God's daily guidance for our lives. "I am the light of the world: he that followeth me shall not walk in darkness, but shall have the light of life" (John 8:12). Since there is no darkness in God, "if we walk in the light as he is in the light" (1 John 1:7), there remains no excuse for any darkness in our lives. "For God, who commanded the light to shine out of darkness, hath shined in our hearts, to give the light of the knowledge of the glory of God in the face of Jesus Christ" (2 Corinthians 4:6). HMM