First of all we need to let the bible interpret itself. In Matthew 13:37-39 Jesus interprets all the terminology concerning the harvest for us: He answered and said unto them, He that soweth the good seed is the Son of man; The field is the world; the good seed are the children of the kingdom; but the tares are the children of the wicked one; The enemy that sowed them is the devil; the harvest is the end of the world; and the reapers are the angels.
1 The sower of the good seed is Jesus
2 The field is the world
3 The good seed are the children [sheep] of the [millennial] kingdom
4 The tares are the children [goats] of the wicked one [Antichrist]
5 The sower of the tares is the devil
6 The harvest is the end of the world [age]
7 The reapers are the angels
The identity of the harvest and reapers proves that this is not referring to a church age harvest of souls. Because this age does not end with the rapture but with second coming of Christ to the earth which is at least 7 years after the rapture of the church. Secondly, at the second coming of Jesus to the earth, he will send forth his angels to gather his elect [of Israel] from the 4 directions of the earth back to their homeland. But at the rapture God himself will catch away his church. If the harvest in Mt 13:39 is referring to the end of this age which is marked by the second coming of Jesus to the earth, then it must also refer to the same event when it's mention in other places in the gospels.
Matthew 9:35-38 says, And Jesus went about all the cities and villages, teaching in their synagogues, and preaching the gospel of the [millennial] kingdom, and healing every sickness and every disease among the people. But when he saw the multitudes, he was moved with compassion on them, because they fainted, and were scattered abroad, as sheep having no shepherd. Then saith he unto his disciples, The harvest truly is plenteous, but the labourers are few; Pray ye therefore the Lord of the harvest, that he will send forth labourers into his harvest.
Matthew 10:1,5-7 states, And when he had called unto him his twelve disciples, he gave them power against unclean spirits [demons], to cast them out, and to heal all manner of sickness and all manner of disease. These twelve [apostles] Jesus sent forth, and commanded them, saying, Go not into the way of the Gentiles, and into any city of the Samaritans enter ye not: But go rather to the lost sheep of the house of Israel. And as ye go, preach, saying, The kingdom of heaven ['s rule on earth] is at hand. Heal the sick, cleanse the lepers, raise the dead, cast out devils [demons]: freely ye have received, freely give.
Now for some observations. Jesus preached in the synagogues which are Jewish. The message he preached was the gospel of the kingdom. This refers to the kingdom age on earth which will last for 1,000 years. Remember the harvest is the end of the age. In this case the end of the age of the Law. But when the Jews rejected Jesus' offer to restore the kingdom to Israel the kingdom age was postponed until 7 years after the rapture of the church. The reason the laborers are few is they literally only numbered 12 in total at this point. Of course, referring to the 12 apostles. In Luke 10 he adds 70 disciples to the number of laborers which brings the total number of laborers to 82. Notice, the message of the 12 apostles and the 70 disciples are the same. Jesus told the 12 apostles in Matthew 10:7 And as ye go, preach, saying, The kingdom of heaven is at hand. And in Luke 10:9 say unto them, The kingdom of God is come nigh [near] unto you. The reason the kingdom was at hand/near them is because the King was on earth with them in the person of Jesus. Because you can't have a kingdom without a King to rule it. What is this harvest that Jesus was speaking about? According to Matthew 13:38 the good seed are the children of the [millennial] kingdom. So, the harvest would be a product of the growth of the good seed. The harvest field into which Jesus and his laborers were to go was Jewish only according to Matthew 10:5-7, These twelve Jesus sent forth, and commanded them, saying, Go not into the way of the Gentiles, and into any city of the Samaritans enter ye not: 6But go rather to the lost sheep of the house of Israel. And as ye go, preach, saying, The kingdom of heaven is at hand. This proves that the harvest that Jesus was sending his apostles into had nothing to do with the church age. It is also very interesting to note that the word harvest does not appear in the Acts or the epistles. After it appears in the gospels it does not appear in the bible again until the latter end of Revelation. Acts 10:34 sheds further light on the intended audience in regard to the harvest. Then Peter opened his mouth, and said, Of a truth I perceive that God is no respecter of persons: But in Matthew 10:6 Jesus is a respecter of persons. He is respecting the Jews over the Gentiles. This reveals that the message preached by Peter and the apostles in the Acts of the Apostles must be a different message than was preached by the apostles in the 4 gospels. The differences are this:
In the 4 gospels, the apostles are preaching the gospel of the millennial kingdom which was prophesied of in the Old Testament. The reason the apostles would say the kingdom is at hand or nigh/near is because the King was near. This is why the words king and kingdom are used interchangeably in the bible. Because you can't have a king with no subjects to rule and you can't have a kingdom without a king to reign over them. In the 4 gospels the church age was still yet in the future according to Matthew 16:18, And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it. In Acts the Apostles were preaching the message of the church age which according to Acts 2:38 is: Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost. The kingdom preached in the gospels is an external one and the kingdom preached in Acts is an internal one. The kingdom preached in the gospels is a worldwide theocratic kingdom over which Jesus will reign over the earth. And the kingdom preached in the Acts is a spiritual kingdom that one must be born into by water and the Spirit baptism. In this kingdom the king lives in our hearts through his indwelt spirit causing us to live in the realm of Christ. When Israel rejected their king and therefore their kingdom the setting up of the kingdom was postponed. This was illustrated in Luke 19:11-12, ...he added and spake a parable, because he was nigh to Jerusalem, and because they thought that the kingdom of God should immediately appear. He said therefore, A certain nobleman [Jesus] went into a far country [heaven] to receive for himself a kingdom, and to return. Because according to verse 27 they didn't want Jesus to reign over them. Now the kingdom will not be set up until the nobleman/Jesus returns from the far country/heaven. Even when Jesus was on the verge of his ascension into heaven the apostles still were not grasping that Jesus had postponed the kingdom. This is according to Acts 1:6-7: When they therefore were come together, they asked of him, saying, Lord, wilt thou at this time restore again the kingdom to Israel? And he said unto them, It is not for you to know the times or the seasons, which the Father hath put in his own power. The reason we cannot know the time when God will restore the kingdom to Israel is because we don't know the time of the rapture. We do know he will restore the kingdom to Israel 75 days after his second return to the earth. We also know his second coming to earth will be 7 years after the rapture of the church.The preaching of the gospel of the kingdom will resume after the rapture of the church according to Matthew 24:14: And this gospel of the [millennial] kingdom shall be preached in all the world for a witness unto all nations; and then shall the end [of the age] come. It will be preached by the 144,000 Jews from the 12 tribes of Israel during the first half of the tribulation and by the 2 witnesses, Moses & Elijah, during the last half of the tribulation. At Jesus' first coming the gospel of the kingdom was preached by his 12 apostles and the 70 disciples.
So in summary, the message of the harvest is the preaching of the gospel of the kingdom. And its audience was Jewish only. It was first introduced by the John the Baptist. The message was rejected by Israel and the setting up of the kingdom age on earth was postponed until Jesus' second coming to earth. In the mean time the kingdom took on mystery form between his first and second comings. This mystery form of the kingdom is referred to as the church age. The reason the church age is referred to as a mystery is because it was not revealed by the Lord to the Old Testament prophets as revealed by Ephesians 3:5-9: Which in other ages [the church age] was not made known unto the sons of men, as it is now revealed unto his holy apostles and prophets by the Spirit; That the Gentiles should be fellowheirs [with the Jews], and of the same body [the church], and partakers of his promise in Christ by the gospel [our identification with Jesus' death, burial and resurrection]: Whereof I was made a minister, according to the gift of the grace of God given unto me by the effectual working of his [indwelt holy ghost] power. Unto me, who am less than the least of all saints, is this grace given, that I should preach among the Gentiles the unsearchable riches of Christ; And to make all men see what is the fellowship of the mystery [of the church age], which from the beginning of the world hath been hid in God, who created all things by Jesus Christ:
This is why the rapture referred to as a mystery in 1 Corinthians 15:51: Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed, Because if the church age was a mystery, naturally the rapture would also be a mystery. After the church age has run its course on earth by its exodus into heaven via the rapture then the preaching of the gospel of the kingdom will resume again. The harvest that results from the preaching of the gospel of the kingdom will be reaped at the second coming of Jesus' to the earth.
Now we want to connect all the dots. Matthew 13:39 definitely fixes the time of the harvest at the end of the age. You must keep in mind that in God's prophetic program for Israel there are only 2 ages:
1 The dispensation of Law
2 And the 1,000 year kingdom age
So, when Jesus came to Israel the first time he came to bring an end to the age of Law and introduce the Kingdom Age. But Israel rejected her Messiah and therefore the age of law was suspended and the kingdom entered into a mystery period called the church age. But after the church age ends on earth with its rapture into heaven the Lord will turn his focus back to Israel. He will pick back up with them where he left off with them which is under the dispensation of law. This is why the Jews will rebuild their temple, after the rapture, and begin to offer animal sacrifices again as part of their worship unto the Lord. The first time Jesus came to Israel he sent his 12 apostles along with the 70 disciples into the harvest field of his people. Their message was the kingdom age was at hand. In the last 7 years [the tribulation period] preceding his second coming he will first send the 144,000 sealed Jews and then his 2 witnesses, Moses & Elijah, into the harvest field of his people again preaching gospel of the kingdom age. But this time the faithful Jews will receive their king and therefore their kingdom. As a result this will bring down the curtain on the age of law as far as Israel is concerned. Consequently, this time the harvest will finally be reaped. The wheat will finally be gathered into the barn [Mt 13:30] which is representative of the saved people who will be allowed to enter the millennial kingdom.
In closing, we are now able to understand why Jesus said that the harvest was the end of the age. Furthermore, it is now revealed to us that the age Jesus was referring to was the age of law and not the church age which is repeatedly wrongly interpreted. Now we know why he told his apostles to go only to Israel with the gospel of the kingdom. The gospel of the kingdom and its resulting harvest pre-dated the church age at the first coming of Jesus and it will post date the church age at his second coming. Remember Jesus also said that the reapers of the harvest are the angels. This why Matthew 24:31 says And he shall send his angels [reapers] with a great sound of a trumpet, and they shall gather [the harvest] together his elect [the Jews] from the four winds [of diections of the earth], from one end of heaven to the other. They will be gathered back to their homeland of Israel. Then Jesus will restore the kingdom to Israel. She will be restored to her rightful position as the head of nations instead of the tail. Jesus will then establish his throne in Jerusalem and install his government of peace over the whole earth.
It is interesting to note that one definition of harvest is "a supply of anything gathered at maturity and stored." This is opposite of our state of being born again of the Spirit. Instead of being mature we are new babes in Christ. After we are born again of the Spirit Jesus did not call us harvesters but witnesses, which means "a person or thing that affords evidence." It is interesting to note that one definition of evidence is "a sign." Compare with Mark 16:17, And these signs [evidences] shall follow them that believe; In my name ...they shall speak with new tongues; This begs the question are we harvesters or witnesses? Acts 1:8 gives us the answer, we shall be witnesses unto Jesus after are empowered by the Holy Ghost. Because we can give a first hand account of our born again of the Spirit experience. And our speaking in tongues when the Spirit entered us is the evidence of that, therefore making us a witness. Now we understand the harvest is the gathering of the Jews into the Millennial Kingdom and has no application to the present day church age.