Reference: Day Of The Lord
The day in which Jehovah was expected to punish sinful Hebrews and the enemies of Israel, and to establish at least the righteous remnant of His people in political supremacy. The Hebrews believed implicitly that their God Jehovah was certain to defeat all rivals. Before Amos this view had not reached a definite eschatology, and probably involved only a general expectation of the triumph of Israel and Israel's God. With Amos, however, the conception of punishment became less ethnic and more moral. The sins of Israel itself deserved punishment, and Amos declared that the luxury of the nation, with all its economic oppression, had grown hateful to Jehovah, and unless abandoned would bring fearful punishment (Am 2:6-8; 3:9-15; 5:10-13; 6:4-8). The righteousness of Jehovah demanded that the sins of His people as well as those of the heathen should be punished. After Amos the thought of an awful day of Divine punishment was extended from Israel to a world of sinners. According to Zephaniah (Am 1:2-15; 2:4-15), punishment was now to come upon all wicked persons, both Jews and Gentiles, because of wrong. So, too, the unknown prophet who wrote under the name of Malachi. Ezekiel (Eze 30:2 f., Eze 34:12; 39:8 f.), however, reverted to the same national thought of a 'day of battle,' in which Jehovah would conquer all Israel's foes; and to some extent this same national idea is represented by Joel (Joe 2:18-27). With the later prophets there is to be seen an element of reconstruction as well as punishment in Jehovah's action. Sinners, whether Jews or Gentiles, are to be punished, but a pious remnant is to be saved, the beginnings of a new Israel.
It is clear that this conception of a great Day of Jehovah underlies much of the Messianic expectation of apocryphal literature. The establishment of a remnant of a pious Israel was the germ of the hope of the Messianic kingdom; and the Day of Jehovah itself became the Day of Judgment, which figures so largely in both Jewish and Christian Messianism. It fact, it is not too much to say that the eschatology of Judaism is really a development of the implications of the prophetic teaching as to the Day of Jehovah.
This cannot be separated from Messiah's day. It is often characterised by judgement: "A day of darkness and of gloominess, a day of clouds and of thick darkness . . . . the day of the Lord is great and very terrible." Joe 2:2,11,31; Mal 4:1. "The day of the Lord so cometh as a thief in the night; for when they shall say, Peace and safety; then sudden destruction cometh upon them." 1Th 5:2-3. "The day of the Lord will come as a thief in the night; in the which the heavens shall pass away with a great noise, and the elements shall melt with fervent heat, the earth also and the works that are therein shall be burned up." 2Pe 3:10. This scene is followed by 'THE DAY OF GOD' in 2Pe 3:12, which ushers in the new heavens and the new earth.
It is important to keep the 'day' quite distinct from the coming of the Lord to fetch His saints; for many have misapplied the term, and it has been constantly asserted that the Second Epistle to the Thessalonians was written to show the saints that it was wrong to be expecting the return of the Lord; whereas the fact is they thought the day of the Lord had come (though the First Epistle keeps the two things quite distinct: compare 1Th 4:13-18 with 1Th 5:1-4), and this could not come until Antichrist was revealed. There will be judgements before the millennium, and there will be judgements after the millennium, so that we may regard the Day of the Lord as extending through the millennium: it will be 'the Lord's' day in contrast to 'man's' day.