Enter into the rock, and hide in the dust, from the terror of the Lord, and from the glory of his majesty. The haughty eyes of people shall be brought low, and the pride of everyone shall be humbled: and the Lord alone will be exalted in that day. For the Lord of hosts has a day against all that is proud and lofty (Isaiah 2:10).First we note that a day of the Lord is not a period of 24 hours. The prophets expected invasions with armies marching in from Egypt and Assyria (Isaiah 7:18-20).
Nor is a day of the Lord the end of human existence. There will be terrible devastation but the day of the Lord is followed by the remaining people keeping cows and sheep (Isaiah 7:21-25).
The day of the Lord will also result in renewed faith. "On that day the remnant of the house of Israel and the survivors of the house of Jacob will no more lean on the one who struck them, but will lean on the Lord, the Holy One of Israel, in truth" (Isaiah 10:20).
One of the great days of the Lord in the Old Testament period was the toppling of Babylon and its ruthless empire. The end is described in Isaiah 13, and Isaiah uses the language of portents such as the sun being darkened, the moon not giving its light, and the stars falling. These are metaphorical of a great city's sun being darkened and the great and mighty being toppled from their pride and power. "The stars of the heavens and their constellations will not give their light; the sun will be dark at its rising, and the moon will not shed its light . . . I will make the heavens tremble, and the earth will be shaken out of its place" (Isaiah 13:10, 13; 24:21-23).
The prophets adopted the same metaphorical portent language to speak of the destruction of the northern kingdom and of Jerusalem by the Babylonians in 587 BC (Joel 2:10, 30-31; 3:15; Jeremiah 13:10, 13). Jesus very deliberately chose the same language to speak of the toppling of the Jerusalem religious establishment by the Romans in AD 70 (Matthew 23:26; 24:29; Mark 13:24-25; Luke 21:5; referring back to Isaiah 13: 6, 10; 24:23; 34:1-4; Jeremiah 4:23-28; Ezekiel 32:7).
Jesus also used the metaphor of birth pangs, as did the Old Testament prophets, to describe the painful signs of the end in that generation (Matthew 24:8; Mark 13:8; see Isaiah 13:8; Jeremiah 6:24; 22:23; Micah 4:10).
It was in this sense that the New Testament writers viewed themselves as in the last days. "Long ago God spoke to our ancestors in many and various ways by the prophets, but in these last days he has spoken to us by a Son" (Hebrews 1:1,2). "You must understand that in the last days distressing times will come" (2 Timothy 3:1). Evidently the early Jewish Christians pictured themselves as living in the last days of that period in their history.
By his quotation from the prophet Joel on the day of Pentecost, Peter viewed the outpouring of the Holy Spirit as the prelude to the end that Jesus had predicted. "In the last days it will be, God declares, that I will pour out my Spirit upon all flesh. . . I will show portents in the heavens above and signs on the earth below, blood, and fire, and smoky mist. The sun shall be turned to darkness and the moon to blood, before the coming of the Lord's great and glorious day" (Act 2:17-20; compare Matthew 24:29; Mark 13:24-25).
As we will see in the next three chapters, the "great and glorious day" (Acts 2:20) seems to be the coming of the Lord in judgment on Jerusalem in that generation, not some long delayed coming in the year 2,000.