Dictionary of Biblical Words:
An expression figuratively applied to the present time of Christ’s absence, who is the Light and Sun of the new creation. The Christian is not of the night, although in the night (1 Thess. 5), but is of the day—hence is to walk and watch until the Lord’s return, as the bright and morning Star, before He rises as the Sun of righteousness, to usher in the millennial day. Individually, during the night, the believer is to shine like a star; collectively, the church may be compared to the moon, showing with a reflected light the beauties of her absent Lord.
Boyd’s Bible Dictionary:
The Hebrew day, from sunset to sunset, embraced the entire night
(Gen. 1:5). Death (John 9:4); sin (1 Thess. 5.5); sorrow, sin, and death (Rev. 21:25; 22:5).
Concise Bible Dictionary:
Used symbolically for:
1. Death, a time “when no man can work” (John 9:4).
2. The moral darkness of the world, in which men sleep and are drunken (1 Thess. 5:7).
3. The period of Christ’s rejection, which is far spent, and the “day” at hand (Rom. 13:12). There will be no night of moral or spiritual darkness in the heavenly Jerusalem (Rev. 21:25; Rev. 22:5).