Revelation 14:18

another angel came out from the altar
The mention of the altar connects the upcoming vintage of wrath with the cry of the souls under the altar at the opening of the fifth seal. “And they cried with a loud voice, saying, ‘How long, O Lord, holy and true, until You judge and avenge our blood on those who dwell on the earth?’ ” (Rev. Rev. 6:10+). God had told them that they should rest until the remaining number of their fellow servants would be killed as they were. That time has now come. who had power over fire
This may be the same angel who offered the prayers of the saints with incense “upon the golden altar which was before the throne” (Rev. Rev. 8:3+). There, after offering the prayers, he filled his censer with fire from the altar and threw it to the earth prefiguring the series of trumpet judgments (Rev. Rev. 8:4-6+). Similarly, it was “a voice from the four horns of the golden altar which is before God” which resulted in the release of the four angels bound at the Euphrates bringing the plague of demonic horsemen. This final vintage of wrath is also motivated by mountains of prayer by the saints of all times and ages for righteous judgment and vindication by God. This is the baptism of fire spoken of by John the Baptist. In his warning to the Pharisees and Sadducees who were coming to his baptism, he indicated that the One following after him would initiate two baptisms. Every person living would receive one or the other.

I indeed baptize you with water unto repentance, but He who is coming after me is mightier than I, whose sandals I am not worthy to carry. He will baptize you with the Holy Spirit and fire. His winnowing fan is in His hand, and He will thoroughly clean out His threshing floor, and gather His wheat into the barn; but He will burn up the chaff with unquenchable fire. (Mtt. Mat. 3:11-12) [emphasis added]

John answered, saying to all, “I indeed baptize you with water; but One mightier than I is coming, whose sandal strap I am not worthy to loose. He will baptize you with the Holy Spirit and fire. His winnowing fan is in His hand, and He will thoroughly clean out His threshing floor, and gather the wheat into His barn; but the chaff He will burn with unquenchable fire.” (Luke Luke 3:16-17) [emphasis added]

The term and with fire is better translated “or with fire.” The immediate context certainly indicates that to be baptized with fire is the result of judgment (notice the reference to purging and burning in the next verse). Other than the visible tongues (billows) of fire which appeared over the disciples’ heads at Pentecost, references to fire burning up unprofitable chaff refer to judgment rather than cleansing. The threshing fan (Mtt. Mat. 3:12) refers to a wooden shovel used for tossing grain into the wind in order to blow away the lighter chaff, leaving the good grain to settle in a pile. The chaff would then be swept up and burned, the unquenchable fire refers to the eternal punishment of hell or the lake of fire.1

gather the clusters of the vine of the earth
Joel foresaw the vintage of wrath associated with the Day of the Lord:

Let the nations be wakened, and come up to the Valley of Jehoshaphat; for there I will sit to judge all the surrounding nations. Put in the sickle, for the harvest is ripe. Come, go down; for the winepress is full, the vats overflow-For their wickedness is great. Multitudes, multitudes in the valley of decision! For the day of the LORD is near in the valley of decision. (Joel Joel 3:12-14)

The reason that these vines will be trodden is that they are wild grapes. Like His chosen nation Israel, those on the earth had not born the fruit God intended.

For their vine is of the vine of Sodom and of the fields of Gomorrah; their grapes are grapes of gall, their clusters are bitter. Their wine is the poison of serpents, and the cruel venom of cobras. (Deu. Deu. 32:32-33)

Now let me sing to my Well-beloved a song of my Beloved regarding His vineyard: My Well-beloved has a vineyard on a very fruitful hill. He dug it up and cleared out its stones, and planted it with the choicest vine. He built a tower in its midst, and also made a winepress in it; so He expected it to bring forth good grapes, but it brought forth wild grapes. And now, O inhabitants of Jerusalem and men of Judah, judge, please, between Me and My vineyard. What more could have been done to My vineyard that I have not done in it? Why then, when I expected it to bring forth good grapes, did it bring forth wild grapes? And now, please let Me tell you what I will do to My vineyard: I will take away its hedge, and it shall be burned; And break down its wall, and it shall be trampled down. (Isa. Isa. 5:1-5) [emphasis added]

for her grapes are fully ripe
God allows evil to have its full fruit for several reasons. First, He provides ample opportunity for the godless to repent and seek forgiveness and restoration. Secondly, He allows the depth of sin to have its full development in those who have forever turned their back on redemption. “But in the fourth generation they shall return here, for the iniquity of the Amorites is not yet complete” (Gen. Gen. 15:16). Although His patience and mercy are abundant, He must eventually judge in order to vindicate His character: “The righteous shall rejoice when he sees the vengeance; He shall wash his feet in the blood of the wicked, so that men will say, ‘Surely there is a reward for the righteous; surely He is God who judges in the earth’ ” (Ps. Ps. 58:10-11).

Notes

1 Jerry Falwell, Edward D. Hindson, and Michael Woodrow Kroll, eds., KJV Bible Commentary (Nashville, TN: Thomas Nelson, 1997, c1994), Mtt. 3:11.

Read Revelation 14:18