8 For you were once darkness, but now you are light in the Lord. Walk as children of light
Verses 8 to 14 deal with walking in spiritual light.
The “for” indicates the reason why believers should not partner with unbelievers in their terminal values.
you were once darkness,
The Christian’s past before becoming a believer was one of spiritual “darkness.” Emphasis is on the word “were.” Believers were in a state of darkness before their salvation. We were under the domain of Satan (Jn 3:19-21).
but now you are light in the Lord.
Note the contrast between “were” in the previous phrase and the word “are” in this phrase. The present tense of “are” shows our new spiritual state—we are light (Co 1:13). God delivered Christians from darkness to spiritual light (Jn 3:21; 8:12; Ro 13:12; 1 Th 5:4-5). That “light” came from their position “in the Lord” and their Lord is the light (Jn 8:12).
Walk [live] as children of light
“Walk” means to order one’s behavior or conduct one’s life. The Greek indicates that “walk” is a command and it is to be followed habitually (present imperative). We are to order our lives as “children of light”—that is, God’s children. We conduct our lives according to our spiritual birth, as born-again ones. It is our nature that impels our walk.
Since the Christian has the status of being in the Lord who is the light, they should walk as “children of light.” Their walk should correspond to their status. They should enlighten others as to what is true. “Children of disobedience” and “children of light” are put in contrast.
Becoming a Christian involves a change of sphere from darkness to light.
Before their conversion Christians were not just in darkness, we were darkness. Now that we have become believers we are light itself. Something radical happened to the believer. Believers are not only to walk in the light, they are light itself.
Christians belong to the realm of light and are not to fellowship with the values of sinners. We are the light of the world (Mt 5:14). We are God’s light to a world in darkness. Enlightened people shed light on others.
Although we are now the children of the light, much darkness remains in us. The difference now that we are Christians is that we are not in total darkness anymore. We know something of God, His grace, and His plan for us. This was a radical change for our lives.