The word of the day is “light.” In our reading of 1 Thessalonians 5:1-8, St. Paul writes that the day of the Lord’s return will surprise many who are heedless and unprepared. But not his congregation. They are “sons of light and sons of the day” (vs. 5:5). They live in the daytime of Christ’s light. Even so, Paul admonishes them to stay awake, sober, vigilant, and ready to greet the Lord when He comes as Lord and Judge of the world.
Paul’s declaration that the faithful are children of the light arises naturally from the thought that the Lord will come “like a thief in the night” (vs. 2). The analogy of the burglar who breaks into a house under the cover of darkness appears often in New Testament. The Lord Himself spoke about such a thief, “… if the master of the house had known what hour that the thief would come, he would have watched and not allowed his house to be broken into (Matthew 24:43). But Paul added that the robber arrives in the darkness of night. After that, the same image occurs four more times.
In our reading, Paul extends the familiar analogy to contrast what it means to live in the day and in the night. The Greek word for “darkness” refers to spiritual ignorance and moral corruption (Strong’s #4653, 220). Those who dwell in such darkness shun the light of truth and goodness lest their deeds are exposed (John 3:20; Ephesians 5:13). The Book of Job describes their behavior graphically in poetry, “The murderer rises at dusk to kill in the night like a thief.” And “the adulterer waits for twilight saying, ‘No eye will see me’ and he disguises his face” (Job 14-15).
Paul warns that the faithful must have nothing to do with the “unfruitful works of darkness” of these wrongdoers (Ephesians 5:11). Rather they should “cast off the works of darkness and put on the armor of light” (Romans 13:13). Thus, the Apostle exhorts the faithful to “live properly as in the day” (Romans 13:13). That is, they should live decently and not shamefully (Strong’s #2156, 107). To this end, the Apostle reminds them, “You were once darkness, but now you are light in the Lord. Live as children of light” (Ephesians 5:8).
Adopted as Children of the Light
We might respond to Paul’s words to the Thessalonians with a practical question. How does it happen that those who once walked in the darkness of sin now live in the light of goodness and godliness? The answer is that it is the work of God who adopts the faithful as His own “children of light” (1 John 1:5). How? The sacrament of Holy Baptism is called “illumination” because in this Mystery, Christ fills our hearts with the brightness of His light. The Lord promises that those who respond by following Him no longer “walk in darkness but have the light of life” (John 8:12). Moreover, those who believe in Him as the Light of God become “sons of the light” (John 12:36.
Always Living in the Day
Yet, these thoughts lead to another question. If Christ has brought us out of darkness into the brightness of His goodness, truth, and righteousness, why should Paul have to admonish us to stay awake, remain alert, and be sober? St. John Chrysostom answers, “To be in the day depends on ourselves” (NfPf1 13, 362). In physical life, wakefulness is not entirely up to us. Without our willing it, night comes upon us. And sleep soon overtakes us. But in the spiritual life, we have the power to live as if it is always day. And in the light of day, we can be constantly vigilant. Chrysostom explains, “to shut the eyes of the soul, and to bring on the sleep of wickedness is not of nature, but our own choice” (NfPF1: 13, 362). We can choose whether to live in the day or in the night. If we live in the darkness of this world, we are bound to be sound asleep in sin when the Lord returns (vs. 7). Moreover, if we are caught up in the “works of darkness,” then the Light of Christ will expose and judge what we have hidden. However, if we live as the sons and daughters of the light, Christ will bring us into the far greater brightness of His glory.
In the last verse of our reading, Paul writes, “But let us who are of the day be sober, putting on the breastplate of faith and love, and as a helmet, the hope of salvation (8). Chrysostom comments that it is not enough for us to be “children of the light” and to live in the daylight of Christ, our hope. We must also be armed. If we are not equipped to fight against the ways of darkness, we are vulnerable to the devil’s attack. Therefore, Paul advises us to put on faith and love to shield our hearts from the passions. And we should put on the hope of salvation as a helmet to protect our minds from deceit and despair. (NfPf1 13,363.) Our Nativity Fast is a good opportunity for us to build fortify ourselves with these and other weapons of the Spirit.
 The allegory is found in 1 Thessalonians 5:2 and 5:4, 2 Peter 3:10, and Revelation 3:3 and 16:15