One of the great themes of the Bible is that of the harvest. In the Old Covenant Scriptures, the three great Holy Day festivals centered around the spring and fall harvest seasons. They not only celebrated real occurrences in the establishment of the nation of Israel, but they also foretold the, then, future coming of the Messiah, the Holy Spirit and the final Judgment by the great King. The theme of the harvest also appears in the New Covenant Scriptures, and this is particularly so in Jesus’ parables. So, the theme of harvest clearly portrays the subjects of judgment and salvation in the Gospel narratives.
Outside of the Gospels, the word harvest (therismos – G2326) is mentioned only in Revelation 14:15. There the Lord, Jesus, is represented as the Son of Man (Revelation 14:14) having a golden crown, and is sitting on a cloud, and in his hand is a sharp sickle.
From the very beginning of the Gospel narratives the theme appears in the ministry of John the Baptist, who came in the spirit and power of Elijah (Matthew 17:11-13), as a forerunner of Jesus:
“The axe is already laid at the root of the trees; therefore every tree that does not bear good fruit is cut down and thrown into the fire. As for me, I baptize you with water for repentance, but He who is coming after me is mightier than I, and I am not fit to remove His sandals; He will baptize you with the Holy Spirit and fire. His winnowing fork is in His hand, and He will thoroughly clear His threshing floor; and He will gather His wheat into the barn, but He will burn up the chaff with unquenchable fire.” (Matthew 3:10-12 NASB)
Notice the harvest language in the underlined portion of the excerpt above. Moreover, notice that the harvest tool, the winnowing fork was already in Jesus’ hand. In other words, it was the time of harvest even before Jesus came on the scene. In fact, Jesus, himself, declared the fields were already white to harvest (John 4:35). Another thing we need to hold up for consideration is the fact that the unfruitful trees and the useless chaff would be burned, so the idea of judgment also appears during the time of the harvest, which, itself portrays the idea of resurrection (cp. 1Corinthians 15:20-23). This is the context of the preaching of the Gospel during the first century AD!
Jesus tells us that the harvest was to transpire at the end of the age (Matthew 13:39), and we are told that Jesus was sent in the last days or the end of the age (Hebrews 1:1-2; 9:26). Daniel, also, spoke of that very time—the time of judgment and the time of resurrection—and the text refers to it as the time of the end:
And at that time shall Michael stand up, the great prince who stands for the children of your people: and there shall be a time of trouble, such as never was since there was a nation even to that same time: and at that time your people shall be delivered, every one that shall be found written in the book. And many of them that sleep in the dust of the earth shall awake, some to everlasting life, and some to shame and everlasting contempt. And they that be wise shall shine as the brightness of the firmament; and they that turn many to righteousness as the stars forever and ever. But thou, O Daniel, shut up the words, and seal the book, even to the time of the end: many shall run to and fro, and knowledge shall be increased. (Daniel 12:1-4 – emphasis mine)
Daniel also mentioned Michael, who is Christ. In a previous study I showed that Jesus is not an angelic being but Michael is God, and it is he who became Jesus. So, at the time of the end, Jesus would stand up for his people during a time of trouble like no other in the history of Israel, since she became a nation. At that time the resurrection would occur, and Jesus would judge his people. It is in this context that we should read Revelation 14:14-20.
 Although the word harvest doesn’t appear in the epistles, the idea of harvest is clearly preached through the use of kindred words such as reaping (therido – G2325) by both Paul (1Corinthians 9:11; 2Corinthians 9:6; Galatians 6:7-9) and James(James 5:4). Other harvest words include husbandman (georgos – G1092), see 2Timothy 2:6 and James 5:7; and laborer / workman (ergates – G2040), see 2Corinthians 11:13; Philippians 3:2; 1Timothy 5:18; 2Timothy 2:15; James 5:4.