While the English translations give wide variety to their rendering of Amos 5:18, a consistent thread prevails between them. The simple prophet, after having shown his people the sins of the nations, is now preaching to his own people. Their religious transgressions have piled high, and they must now prepare to meet God's wrath in His judgment of them (4:12). They refused to seek Him, so they would not live (5:4-6,14). Judgment would come in the form of foreign invasion, captivity, and destruction. Amos is not speaking of the final judgment at the end of time, but rather God's fulfillment of a promise that went back centuries to the days when the tribes of Israel stood on Ebal and Gerizim. They had forsaken God, and now He was going to judge them.
His own people were filled with hypocrisy. They did not hate evil and love good (5:15). They kept the "form" of religion but they had rejected the "substance" (cf. 5:21ff). As they looked to the future, Amos tells them they should not long for "the day of the Lord." He asks, "For what purpose will the day of the Lord be to you?" For most of them, it was a day of "darkness and not light" and "gloom with no brightness in it" (cf. 5:20).
Regarding the final judgment of all mankind, each of us would do well to ask, "For what purpose will the day of the Lord be to me?" Jesus shows us the available options. It will either be a day of rejoicing and reward, or it will be a day of rejection and rift. For the few, it will be a day to receive the victor's crown. For the many, it will be the first day of an eternity full of total darkness, gnashing of teeth, unending terror, and indescribable pain. It is not enough for that day to be a happy day for spouse, parent, child, sibling, or friend. Their salvation will based on how they lived in their body (2 Cor. 5:10). For what purpose will the day of the Lord be to you? A day for you to eagerly anticipate or for you to continually dread?
The good news is that no matter what we have done in the past, we can come to Christ in obedient faith. He promises to forgive, and He wants to eternally save (2 Pet. 3:9). Dread can be replaced with desire! It is what God wants for you. "For what purpose will the day of the Lord be to you?"