Is it sin for those who have made the covenant with God to celebrate a national holiday? Zechariah 8:19 gives four fasts established by the Jews, none of which has anything to do with God's plan. The fast of the fourth month (9th of Tammuz) marked when the Babylonians entered Jerusalem; that of the fifth month (9th of Ab), the destruction of the Temple; that of the seventh month (3rd of Tishri), the murder of Gedaliah, a governor of Judah; and that of the tenth month (10th of Tebeth), the beginning of the Babylonian siege of Jerusalem.
God nowhere says that they are evil, that He hates them, or that to observe them is sin. In fact, the prophecy in which these fasts appear shows not only God's approval of keeping them, but also that He will turn them into feasts of joy rather than fasts of sorrow.
One might argue, "Yes, but these fasts are solemn and serious in their purpose, and God could hardly be displeased with that." Maybe so, but is God displeased when people have fun rejoicing over His blessings? Hardly! The prophecy clearly shows He wants us to rejoice.
John W. Ritenbaugh
Thanksgiving or Self-Indulgence?
What Are the Fasts Mentioned in Zechariah 8:19?
Unlike the divinely appointed Day of Atonement (Yom Kippur), the fasts mentioned in this verse were of human origin. They were instituted to serve as reminders of four sorrowful events that befell the Jewish nation during the days of Jeremiah and Ezekiel.
The "fast of the fourth month," observed during the month of Tammuz, commemorated the time the city of Jerusalem was broken up (Jeremiah 52:6-7). The "fast of the fifth" was observed on the tenth of Ab, when the Temple and the houses were burned (verses 12-13). The "fast of the seventh" refers to the third of Tishri, when Gedaliah was slain by Ishmael (Jeremiah 40:8; 41:1-3, 15-18). The "fast of the tenth" was kept on the tenth of Tebeth, when the king of Babylon turned against Jerusalem (Ezekiel 24:1-2). This information can be verified in the Jewish Talmud.
As this verse shows, these humanly appointed fasts will be turned into feasts or occasions of gladness when God restores all Israel to His way of life. At last, the people will seek God (verses 20-23) and will be greatly blessed. They will no longer wish to perpetuate the memory of tragic events.
Holy Days: Atonement
Isaiah 58 and Fasting
Other Forerunner Commentary entries containing Zechariah 8:19: