People who are harvested as grapes are least understood and least explained in the scriptures and least discussed by Yahweh's people. (see Grape Harvest) This is probably because it doesn't matter (to them, but it may to us because it affects our understanding of Yahweh' character). These people won't believe anyway (not in this age). These are people who never knew or accepted Christ, or those who knew, but later denied Him. They are the pagans, heathens, agnostics, atheists, gentile unbelievers and rejectors. We are told enough to understand Yahweh's plan, but it is in an obscure "forgotten" prophecy of Isaiah. As a group, these people are represented in Isaiah 63 as Edomites . Their robes are red, appearing as those who have treadeth a winepress. Immediately after asking who they are, Christ reminds the reader that He is "mighty to save" and explains about treading the winepress alone. This occurs after the millennium and after the start of the grape harvest.

Isaiah 63:1-3
Who is this that cometh from Edom, with dyed garments from Bozrah? this that is glorious in his apparel, travelling in the greatness of his strength? I that speak in righteousness, mighty to save. Wherefore art thou red in thine apparel, and thy garments like him that treadeth in the winefat? [wine vat] I have trodden the winepress alone; and of the people there was none with me: for I will tread them in mine anger [forebearance, longsuffering - look it up!], and trample them in my fury; and their blood shall be sprinkled upon my garments, and I will stain all my raiment.

This isn't the only Biblical reference to washing robes in wine. Judah, also, is said to have washed his garments in wine:

Genesis 49:11
Binding his foal unto the vine, and his ass's colt unto the choice vine; he washed his garments in wine, and his clothes in the blood of grapes:

How does wine clean robes? I don't know, but Christ says it, so it must be so. But wait! These people are evil. How can they be saved? Christ gave us a hint that this would happen when He gave us the parable of the Wedding feast. Bad people are gathered (harvested) too. This word also translates as "evil" and "wicked". This is why Christ reminds us that He is mighty to save, and this occurrence in Isaiah occurs after all the righteous (barley and wheat) have already been gathered in.

Matthew 22:10
So those servants went out into the highways, and gathered together all as many as they found, both bad [evil, wicked] and good: and the wedding was furnished with guests.

The grapes, after the harvest of grape souls, are pressed in the winepress by Christ, Himself. Their robes are washed (not by themselves, as the wheat, but by Christ, treading the grapes) in the "blood" of the wine. Literally, this would make them red as described by the men of Bosrah and Judah. But, this may be figurative and they may end up white like the other robes (Remember, those washed in the blood of the cross end up white). Or, maybe they will always wear red robes. This study doesn't have that answer. It is left to the will of our Father and our further understanding.

Many Bible commentators believe that the winepress is an instrument of punishment and that Christ, treading the winepress is punishing the wicked. This doesn't agree with Isaiah's prophecy, where He explicitly says that He will NOT destroy the grapes. Pressing the grapes is a normal (usual) part of the grape harvest, just as threshing is a usual part of the wheat harvest.

Isaiah 65:8
Thus saith יהוה [Yahweh, our god], As the new wine is found in the cluster, and one saith, Destroy it not; for a blessing is in it: so will I do for my servants' sakes, that I may not destroy. The phrase "them all" does not appear in the original and is added by editors. It's amazing how men have tried to pollute Yahweh's clear word, leading us to believe that Yahweh will do something (destroy "some") when He says He will NOT.

This prophecy is about the grape harvest after the millennium. We know that because it also discusses creating new heavens and a new earth. We know that this is after the millennium and just after the New Jerusalem comes from Heaven to the earth. (Revelation 21:1,2)

Isaiah 65:17-19
For, behold, I create new heavens and a new earth: and the former shall not be remembered, nor come into mind. But be ye glad and rejoice for ever in that which I create: for, behold, I create Jerusalem a rejoicing, and her people a joy. And I will rejoice in Jerusalem, and joy in my people: and the voice of weeping shall be no more heard in her, nor the voice of crying.

Fire refers to purification (Luke 3:16, Isaiah 48:10, Psalms 12:6, Zechariah 13:9, Isaiah 4:4). Both fire and sword refer to His word (Jeremiah 23:29, Ephesians 6:17, Revelation 19:15), pleading with men. When they accept His word, they die (spiritually) and are re-born, just as in baptism.

Isaiah 66:15-16
For, behold, יהוה [Yahweh] will come with fire, and with his chariots like a whirlwind, to render his anger with fury, and his rebuke with flames of fire. For by fire and by his sword will יהוה [Yahweh] plead with all flesh: and the slain of יהוה [Yahweh] shall be many.

The "potter" and clay refer to Yahweh (re-)making His creation (the ones who do NOT reflect His image, yet). Their bodies (pots of clay) are so imperfect that they must be broken and re-created. Notice, that the barley and wheat don't have to have their clay pots broken and re-created - only the grapes.

Isaiah 64:8
But now, O יהוה [Yahweh], thou art our father; we are the clay, and thou our potter; and we all are the work of thy hand.

These people, as part of their restoration, must also have clean robes - the robes of the grape harvest. These are cleansed in the "blood of the wine" and they will be acceptable to their maker - fully restored.