Ephesians 5:8

Ye were sometimes darkness, but now are ye light in the Lord. — This expression is unique, and far more emphatic than the more common phrases of “being,” or “walking,” “in darkness” and “in light.” (See Romans 2:9; Colossians 1:2; 1 Thessalonians 5:4; 1 John 1:6; 1 John 2:9.) For here the outward element of light or darkness is said to pervade the inner nature of the soul. (1) Christ is the “true Light,” the “Sun of Righteousness” (John 1:4; John 3:19; John 8:12; John 9:5; John 12:46). His servants are sometimes mere secondary lights (or “candles”) (Luke 11:33; Luke 11:36; John 5:35; 2 Peter 1:19), kindled from His rays; sometimes, like the moon or planets, they are said, as reflecting His light, or as having His light in them (John 12:35), to be actually “the light of the world” (Matthew 5:14), which, however, shines as a mere reflected light, so that “men glorify” not it, but “the Father which is in heaven” (Matthew 5:16). They thus become light, but only “in the Lord:” that is, as being made one with Him. (2) So, on the other hand, they who walk in darkness are said to be themselves darkness — new sources, so to speak, of the darkness which hates and quenches light, both to themselves and to others. “The light” which is in them “becomes darkness;” “and how great is that darkness!” (Matthew 6:23.) As there is a natural delight in giving light, so the reprobate state is distinguished by a horrible pleasure in spreading the cloud of delusion, sin, or unbelief, by which to hide God from man.

Walk as children of light. — So our Lord teaches, “While ye have the light, believe in the light, that ye may become children of light” (John 12:36; comp. 1 Thessalonians 5:5). “Children of light” are they who not only love the light, but also manifest the likeness of the one true Light, “the Father of Lights” (James 1:17), being His children in Jesus Christ.