Dictionary of Biblical Words:
That which God is. It la one of His two essential qualities, the other being Love. All who are brought to God are thus necessarily in the light (Eph. 5:8).
They are no longer darkness or in darkness, but are light and in the light. On this fact rests their responsibility to walk according to it. If they sin, they sin in the light and against the light. This attribute of God is connected with conscience, or the sense of moral responsibility, just as love on the other hand connects itself with the heart, the seat of the affections. God thus, in this double character, answers to both sides of man’s nature. The center of this light is Christ, both now (John 1) and hereafter (Rey. 21:23). The inheritance of the saints is in light, heaven being constantly thus characterized in contrast to the darkness, and outer darkness of hell. Practically the way to be light is to have a single eye (Matt. 6:22).
Boyd’s Bible Dictionary:
First gush of creation
(Gen. 1:3). Frequent source of imagery (Matt. 4:16; Luke 2:32; John 1:7-9).
Concise Bible Dictionary:
Besides the references to physical light as existing distinct from the sun, and then emanating from the sun as the great light-bearer, the term is mainly used in scripture in a moral sense. Light from God is His word revealing Himself, and not only making manifest the dangers here, but acting as a lamp in showing the true path (Psa. 119:105). The Psalmist asked Jehovah to lift upon him the light of His countenance (Psa. 4:6), and declared that Jehovah Himself was his light (Psa. 27:1). As natural light brings vigor and health to the body, so the light of God gives cheerfulness and strength to the soul.
“God is light,” and the Lord Jesus came to the earth as the true light which lighteth every man. He not only exposed all the evil in the world and all the false pretensions of the leaders of Israel; but “the life was the light of men” (John 1:4; John 8:12). Christians are “light in the Lord,” and are exhorted to walk as “children of light” (Eph. 5:8; 1 Thess. 5:5). In the midst of darkness they are set to shine as lights in the world (Phil. 2:15). A grave responsibility rests upon them lest they should not have the heavenly luster that would characterize them as having in their hearts the light of the glory of the Lord. If the light in the Christian become darkness by his not walking in the reality of it, how great is that darkness! (Matt. 6:23).
It has been very properly said that light is appropriately descriptive of God; for light, invisible in itself, manifests everything. Christians, as we have seen, are “light in the Lord,” and thus convict the unfruitful works of darkness; but here we may notice that it is not said of them, as of God, that they are “love,” for love is the sovereign, spring of activity in God.
Strong’s Dictionary of Greek Words:
Meaning:
from the base of 3022; a portable lamp or other illuminator (literally or figuratively)