"For ye were sometimes darkness, but now are ye light in the Lord: walk as children of light" (Ephesians 5:8).
It is one thing to be "light in the Lord." It is another thing to "walk as children of light."
Born again believers in the Lord Jesus Christ represent Him in everything we do. We either reveal Him as He is by faithfulness in expressing His character, nature, and way, or we present a false image by a life that does not reflect our relationship to Him. We are His "ambassadors," and just as earthly representatives either accurately or inaccurately communicate the message of whomever they represent, so do Christians bear the responsibility of being our Lord's means of revealing who He truly is (II Corinthians 5:20).
This is a solemn and tempering truth for every believer. It is meant to be. "Denying ungodliness and worldly lusts, we should live soberly, righteously, and godly, in this present world; looking for that blessed hope, and the glorious appearing of the great God and our Savior Jesus Christ" (Titus 2:12-13). Our world is watching us, and they are either consistently seeing the Lord Jesus in our demeanor, attitudes, words, and deeds as He is, or they are not. Again, we are His lights, His lamps in spiritual substance, being, and relationship. But whether we walk accordingly is a different matter. The glory of God is at stake, as well as our world's seeing of Him in such a manner that it is drawn to Him rather than repelled.
Only the One whom we represent can enable our faithful representation. By His Spirit, the Lord Jesus dwells within us as the flame which illuminates the face of God. The light of such glory must shine forth from us as well, and our response to this truth must be the most serious consecration of faith and submission to the very reason for our existence. Our world is watching. We must be shining.
"They took knowledge of them, that they had been with Jesus."
"Whatsoever ye do, do all to the glory of God."
(I Corinthians 10:31)