What is the unique day known only to the Lord?

Answer:

"In that day there will be no light; the luminaries will dwindle. For it will be a unique day which is known to the LORD, neither day nor night, but it will come about that at evening time there will be light. And in that day living waters will flow out of Jerusalem, half of them toward the eastern sea and the other half toward the western sea; it will be in summer as well as in winter. And the LORD will be king over all the earth; in that day the LORD will be the only one, and His name the only one" (Zechariah 14:6-9).

The book of Zechariah is grouped by the style of prophecy Zechariah delivers. Zechariah 12-14 form a prophecy called the second burden. A "burden" is a prophecy that brings bad news.

1. Zechariah 12:1-9 states that, at some point in the future, God will use Jerusalem to punish the nations, but God will save Jerusalem. "Behold, I am going to make Jerusalem a cup that causes reeling to all the peoples around; and when the siege is against Jerusalem, it will also be against Judah. It will come about in that day that I will make Jerusalem a heavy stone for all the peoples; all who lift it will be severely injured. And all the nations of the earth will be gathered against it" (Zechariah 12:2-3). This sets up the basic topic for the rest of the burden.
2. Zechariah 12:10-13:9 tells us how God will accomplish this salvation.
   1. "I will pour out on the house of David and on the inhabitants of Jerusalem, the Spirit of grace and of supplication, so that they will look on Me whom they have pierced; and they will mourn for Him, as one mourns for an only son, and they will weep bitterly over Him like the bitter weeping over a firstborn" (Zechariah 12:11). This refers to Jesus' death on the cross (John 19:37).
   2. At the same time, God will open a fountain for cleansing (Zechariah 13:1). This refers to our redemption through Jesus' shed blood (Hebrews 9:13-14).
3. The same period will see the general end of idolatry, possession by unclean spirits, and prophecy. This refers to the first- and second-century period as Christianity spread throughout the Roman Empire, but it began with Jesus and the early disciples (Luke 10:18).
4. The Shepherd would be struck, and the sheep would be scattered (Zechariah 13:7-9; Matthew 26:31,56; Mark 14:27,50). The period would be accompanied by persecutions that will refine God's people (Acts 2:21; Romans 10:12-14; Hebrews 8:10).
5. Then the nations will wage war on Jerusalem (Zechariah 14:1-2). This refers to Titus's siege and conquest of Jerusalem in 70 A.D. (Matthew 24:22; Romans 9:27-29). Some suggest that Jerusalem is being used as a symbol of the church and that what is being described is the persecution of the church.
6. In retribution, God will battle the nations (Zechariah 14:3-7). This leads to Israel's downfall (Mark 13:26-27).
7. But even as this takes place, living water will flow from Jerusalem in all directions (Zechariah 14:8-11). Despite the persecution, the gospel (the living water) is spread.
8. God will strike those who battled Jerusalem (Zechariah 14:12-15). This is another reference to the fall of the Roman Empire.
9. Those who survive the downfall will come to worship God, but those who do not will be punished (Zechariah 14:16-21).

In other words, Zechariah's Second Burden is about the Son of God coming to bring salvation to the world and establish the church (Hebrews 12:22-24). While that is good news, it comes about through the death of God's Son, the persecution of God's people, and the punishment of those who oppose God (the Jews and the Romans).

The lack of light is frequently used in prophecies of a failing nation. "Multitudes, multitudes in the valley of decision! For the day of the LORD is near in the valley of decision. The sun and moon grow dark, and the stars lose their brightness. The LORD roars from Zion and utters His voice from Jerusalem, and the heavens and the earth tremble. But the LORD is a refuge for His people and a stronghold to the sons of Israel" (Joel 3:14-16). Speaking of the destruction of Babylon, God declared, "Behold, the day of the LORD is coming, cruel, with fury and burning anger, to make the land a desolation; and He will exterminate its sinners from it. For the stars of heaven and their constellations will not flash forth their light; the sun will be dark when it rises, and the moon will not shed its light. Thus I will punish the world for its evil and the wicked for their iniquity; I will also put an end to the arrogance of the proud and abase the haughtiness of the ruthless" (Isaiah 13:9-11).

Lights guide us and show us the way. As God brings down a nation, He removes the leadership and the wise (Isaiah 19:11-14; 44:25). Government leaders begin making poor decisions that lead to the nation's collapse.

The gloom, where it is neither night nor day, refers to depression that sets in. "Then they will look to the earth, and behold, distress and darkness, the gloom of anguish; and they will be driven away into darkness" (Isaiah 8:22).

Yet, at the end, there will be light. As Jesus died on the cross, the world was covered in darkness for three hours. Gloom settled on the disciples as their hope in the Messiah died. Yet three days later, hope blossomed into glorious daylight as they realized Jesus had risen from the grave. "The people who walk in darkness will see a great light; those who live in a dark land, the light will shine on them" (Isaiah 9:2).

"Do all things without grumbling or disputing; so that you will prove yourselves to be blameless and innocent, children of God above reproach in the midst of a crooked and perverse generation, among whom you appear as lights in the world, holding fast the word of life, so that in the day of Christ I will have reason to glory because I did not run in vain nor toil in vain" (Philippians 2:14-16).