The concept of "firstfruits" is introduced by God in the Old Testament, which Moses presents as part of the Law to the nation of Israel (Ex 23:16-19).

"Firstfruits," the first of the crops and fruit that was harvested, represented the first blessings from God. In an agricultural context, it placed a focus on order and quality, because this was the first to ripen, and the grain or fruit was often the biggest in size. As the first blessing from God, a livestock's firstborn was also seen in the same light as first fruits.

It is in this context that God instructs His people to make first fruits as an offering to Him. The offering was principally to serve as a reminder of His provision and blessing of the Promised Land and to honor Him (Deut 26:1-10; Prov 3:9).

In the first offering recorded in the Bible, God had regard for Abel's offering precisely because it was the first of the "harvest", the firstborn of his flock, whereas Cain did not (Gen 4:3-5).

God stipulated that firstfruits be offered in three national feasts:

Feast of the Unleavened Bread (Ex 23:16; Lev 23:4-14)

Celebrated in the spring (mid March – mid April), this festival was often called Passover (Luke 2:41-43; 22:1), because the Lord's Passover was celebrated the day before the one week Feast of the Unleavened Bread. The Feast of the Unleavened Bread (Hebrew: Hag Hamatzot) begins on a Saturday.

On the second day of the Feast of the Unleavened Bread, the first harvest of barley (first fruits) constituted the grain wave sheaf offering (Lev 23:6, 14). Some commentators mistakenly refer to this day as the "Feast of First Fruits." After this offering, the harvesting of grain was permitted. Agriculturally, barley ripened before wheat.

The second day of the Feast of the Unleavened Bread initiates day one of the countdown of days to the Feast of Weeks (Lev 23:15-16).

Of the New Testament, through Paul, the Holy Spirit conveys an agricultural imagery where the harvest / reaping of human beings is associated with their resurrection; Jesus Christ is "the first fruits of those who are asleep". (1 Cor 15:16-23).

For if the dead are not raised, then not even Christ has been raised; and if Christ has not been raised, your faith is worthless; you are still in your sins. Then also those who have fallen asleep in Christ have perished. If we have hoped in Christ only in this life, we are of all people most to be pitied. But the fact is, Christ has been raised from the dead, the first fruits of those who are asleep. For since by a man death came, by a man also came the resurrection of the dead. For as in Adam all die, so also in Christ all will be made alive. But each in his own order: Christ the first fruits, after that those who are Christ's at His coming, then comes the end, when He hands over the kingdom to our God and Father, when He has abolished all rule and all authority and power. (1 Cor 15:16-24)

Jesus Christ's crucifixion and resurrection coincide with the sequence and timing of these two celebrations: Passover (crucifixion) and the first harvest producing the grain wave sheaf offering (resurrection).

However, when Jesus speaks to the disciples, there is an impression that the harvest takes place within the lifetime of the disciples (Matt 9:37-38; Mark 4:26-29; Luke 10:1-2; John 4:34-38). Similarly, when rebuking Jewish religious authorities with a parable of the kingdom of God (Matt 21:33-44; Mark 12:1-9; Luke 20:9-16), there is a suggestion that the harvest will occur within their lifetime. In these instances, Jesus speaks of the harvest in a different sense - disciples as laborers sowing the gospel, tending to the sanctification of Believers, and harvesting by growing the kingdom of God; the firstfruit is seen as new Believers holy to God.

This can be seen in the apostle Paul's reference to the household of Stephanas (1 Cor 16:15-16):

Now I urge you, brothers and sisters: you know the household of Stephanas, that they are the first fruits of Achaia, and that they have devoted themselves to ministry to the saints; I urge that you also be subject to such as these and to everyone who helps in the work and labors. (1 Cor 16:15-16)

James speaks similarly in the context of sin and salvation (Jam 1:14-18):

But each one is tempted when he is carried away and enticed by his own lust. Then when lust has conceived, it gives birth to sin; and sin, when it has run its course, brings forth death. Do not be deceived, my beloved brothers and sisters. Every good thing given and every perfect gift is from above, coming down from the Father of lights, with whom there is no variation or shifting shadow. In the exercise of His will He gave us birth by the word of truth, so that we would be a kind of first fruits among His creatures. (Jam 1:14-18)

This view of firstfruit is also seen in the Old Testament (Jer 2:3):

"Israel was holy to the Lord,
The first of His harvest.
All who ate of it became guilty;
Evil came upon them," declares the Lord. (Jer 2:3)

Feast of Weeks / Harvest (Ex 23:16; 34:22; Num 28:26)

Fifty days after Passover, after the first day of the Feast of the Unleavened Bread, the Feast of Weeks (Hebrew: Shavuot) took place. God also identifies the Feast of Weeks as the "Feast of Harvest" (Ex 23:14-16), "Feast of the Harvest of Firstfruits" (Ex 23:16), and the day of the grain offering as the "Day of the Firstfruits" (Num 28:26).

The firstfruit grain offering in this seven day festival was wheat.

This 50th day after Passover became known as Pentecost. In the New Testament, this is the day that the apostles were baptized with the Holy Spirit (Acts 1:4-5; Acts 2:1-4). In contrast to the concept of firstfruits as the first harvest of crops, the apostle Paul speaks of the Holy Spirit as dispensing firstfruits!

For we know that the whole creation groans and suffers the pains of childbirth together until now. And not only that, but also we ourselves, having the first fruits of the Spirit, even we ourselves groan within ourselves, waiting eagerly for our adoption as sons and daughters, the redemption of our body. (Rom 8:22-23)

But the wisdom from above is first pure, then peace-loving, gentle, reasonable, full of mercy and good fruits, impartial, free of hypocrisy. (Jam 3:17)

In the context of Pentecost, the Holy Spirit's firstfruits may be understood as enabling God's laborers to sow the gospel, tend to the sanctification of Believers and harvest by growing the kingdom of God.

Feast of Ingathering (Ex 23:16; 34:22)

In contrast to the Feast of the Unleavened Bread and the Feast of Weeks, the Feast of Ingathering (Hebrew: Hag Ha'asip) occurred after the completion of the harvest of the field, vineyard and orchard, around late September - October. The end of the harvest usually included the processing of fruit (i.e. olives to oil, grapes to wine, etc.). This seven day festival, starting on a Saturday, celebrated God's blessing and abundant provision and served as a reminder that the harvest was not by one's skills and efforts alone.

Unique to this feast is God's stipulation to make temporary shelters (Lev 23:40), which is why this festival is also known as the "Feast of Booths" (Deut 16:13; 31:10; Lev 23:34; Neh 8:14-18).

All the native born Israelite were commanded to live in the booths for the entire week (Lev 23:42) so that successive generations would know of the reality of God when He brought the sons of Israel out from Egypt and had them live in temporary shelters (Lev 23:43).

There is an event in the New Testament that is very similar to this celebration. When Jesus Christ returns to fetch His bride the church, the Second Coming describes Jesus Christ and His angels as reaping "as the harvest of the earth is ripe" (Rev 14:14-16; Matt 24:29-31).

Jesus speaks of the "harvest" as occurring at the "end of the age" (Matt 13:24-30, 36-43; Rev 14:14-15), and the firstfruit, the first harvest of Believers, is seen in the 144,000 bond servants (Rev 14:4). Jesus' harvest is with the sense of those who have been gathered in heaven, and the "firstfruits" as possibly a unique class of Believers who served God in a special way.

These are the ones who have not defiled themselves with women, for they are celibate. These are the ones who follow the Lamb wherever He goes. These have been purchased from mankind as first fruits to God and to the Lamb. (Rev 14:4)

When Jesus was on earth and spoke of the kingdom of God in parables, the Parable of the Tares (Matt 13:24-30, 36-43) and Dragnet (Matt 13:47-50) present the separation of Believers from non-Believers as occurring simultaneously.

As Jesus Christ reaps for Believers, His angels reap non-Believers.

The angel is figuratively reaping clusters of ripe grapes (Rev 14:18). The grapes are thrown into the great wine press of the wrath of God (Rev 14:19). The wine press was trodden outside of Jerusalem and produced an enormous amount of blood (Rev 14:20).

When Jesus Christ comes to Armageddon (Rev 16:13-16; 19:11-19), His treading in the wine press (Rev 19:15) that produces the vast amount of blood (Rev 14:20) indicates that this angel's reaping event encompasses a period that includes the final dispensation of God's wrath – specifically all of the bowls and the battle of Armageddon.

The grapes that are thrown into the great wine press of the wrath of God (Rev 14:19) represent evil human beings just before being crushed in judgment.

When the seventh bowl is dispensed, the seventh angel announces, "it is done," to express the end of God's judgment and wrath (Rev 16:17).

When Jesus Christ treads the wine press of the fierce wrath of God (Rev 14:20; 19:15), the wine press metaphor represents divine judgment.

Just as the Feast of Ingathering where the celebration takes place at the conclusion of the harvest, the marriage feast in heaven takes place with the last of God's wrath discharged, which is the conclusion of the reaping by Jesus Christ and His angels (Rev 19:7-9).

"Let us rejoice and be glad and give the glory to Him, for the marriage of the Lamb has come and His bride has made herself ready. It was given to her to clothe herself in fine linen, bright and clean; for the fine linen is the righteous acts of the saints." Then he said to me, "Write, 'Blessed are those who are invited to the marriage supper of the Lamb.'" And he said to me, "These are true words of God." (Rev 19:7-9)