This phrase combines a strictly temporal reference to the day and a reference to the eternal (Lord). This combination, quite typical of the Bible, is an apparent contradiction that can be resolved either by giving priority to the temporal component (whether day or year)—thus imprisoning God within the slots on human calendars—or prioritizing the eternal component by thinking of this day as chosen by God to fulfill his purposes. This second option is characteristic of the Bible. The God of Israel, having created his people by sealing covenants with them, retained authority to set a term to the period when their truancy or faithfulness would be disclosed. Typically, he would choose a time that would surprise them, whether earlier or later than they expected. His verdicts also would be surprising, often condemnation where approval was expected, or vindication where the penitent expected punishment. The primary concern of God's spokespersons was not with the date of the accounting but with its certainty.

Often, the day of the Lord is announced as “coming.” That verb denotes movement, but not a movement of Israel toward a date on the calendar, but rather movement of God toward his people in order to call them to account. Where rebellion flourishes, prophets announce God's imminent coming to lay bare the secrets of hearts (Ezek. 30; Isa. 2.12; 3.18). Where loyalty flourishes in the midst of suffering, they provide consolation and courage by promising speedy intervention by the Most High (Isa. 11–12). The approach of the day would thus be marked by both deep darkness and the shining of the dawn.

The frequent references to God's coming explain the flexibility in the use of terms. The same event could be announced as the hour, the day, the year, or the time (see Time, Units of). The importance of the event could be indicated by articles and adjectives: the day, that day, the great day, the last day. The fearfulness of God's judgment released an array of surreal images: lightning, thunder, earthquake, tidal waves, tumults among nations, all intended to express how terrible it is to fall into the hands of the living God (Isa. 13; 22; Jer. 46.10; Lam. 2; Heb. 10.31; Rev. 16.12–21). Sodom and Gomorrah become stock examples of destruction (Gen 13.10; Matt. 10.15; Luke 17.22–30). It is impossible to organize or harmonize all pictures of God's wrath (Joel 2). But the expectations of doom could be reversed by surprising mercies (Hos. 2; Amos 9:11–15).

In biblical as in later times, false prophets and false messiahs exploited desires to know in advance the signs of the times (Mark 13.6), but others stressed divine secrecy (Mark 13.32; 1 Thess. 5.2–3). God's reckoning of time differs completely from human calculations (Ps. 90.4; 2 Pet. 3.8). It was therefore wrong either to spread panic because of the day's nearness or to counsel despair because of its distance. The function of the references to the day was thus both to warn unsuspecting rebels to watch (e.g., Matt. 24.42–44) and to assure the faithful of the nearness of their salvation (1 Thess. 5.4–11).

Early Christians commonly identified the biblical day of the Lord with the day of the Son of man (Matt. 24.42–44; Luke 17.24, 30; Acts 17.31; Rom. 2.16), when the risen Jesus would act as judge in the heavenly trial of his followers (Matt. 25.31–46). The twelve are also pictured as sharing the throne of judgment (Luke 22.30). Some authors, however, understood the last days to have begun with the ministry of Jesus (John 12.31; 16.8–11; Acts 2.16–21; Heb. 1.2).

Paul S. Minear