In the article “What is Shavuot?” from One for Israel they write…”the Jewish people have been “Counting the Omer” since Passover, which is the countdown to Shavuot. Or perhaps we should say we have been counting up, rather than down? Because counting the days is inevitably leads to a build up of expectation all the way up to Shavuot, which means “weeks” in Hebrew, hence the name “the Feast of Weeks”.

Passover celebrates the time the angel of death passed over the Hebrew houses, and the feast of Tabernacles remembers the desert wandering in tents, but what is the Feast of Weeks all about?

Its main anchor point is Passover, in that it is intrinsically linked to counting the time since Passover and the Exodus event. After counting seven weeks down to the Sunday of Shavuot, the original biblical instructions involve celebrating with animal sacrifices as well as grain and drink offerings, and a good rest. The fruits of the land are celebrated, and it seems to be some sort of harvest festival.

Somewhat randomly, after delineating the required sacrifices and wave offerings, this verse appears:
“And when you reap the harvest of your land, you shall not reap your field right up to its edge, nor shall you gather the gleanings after your harvest. You shall leave them for the poor and for the sojourner: I am the Lord your God.” (Leviticus 23:22)

This commandment is in keeping with the theme of harvest, but seems misplaced in the chapter on biblical feasts. However, the themes of the poor and the sojourner end up playing a significant part in the true, prophetic meaning of the feast. It was thanks to this verse that the Moabite Ruth was able to find the gleanings of the field to survive, and in doing so, met her kinsman redeemer, Boaz. A love story between Jew and Gentile… it should be no surprise then that the story of Ruth has become a significant feature of Shavuot. Moreover, the theme of Jew and Gentile comes into greater focus in the New Testament, when the Feast of Shavuot comes into fulfillment—except that in the New Testament, written in Greek, Shavuot is translated as Pentecost.

Pentecost comes from the Greek word for 50 (pente) after the instruction to count 50 days, 7 weeks. Here’s how it was rather famously celebrated among the disciples of Jesus:
When the day of Pentecost arrived, they were all together in one place. And suddenly there came from heaven a sound like a mighty rushing wind, and it filled the entire house where they were sitting. And divided tongues as of fire appeared to them and rested on each one of them. And they were all filled with the Holy Spirit and began to speak in other tongues as the Spirit gave them utterance. (Acts 2:1-4)

Just as John the Baptist foresaw, Jesus baptized His disciples with the Holy Spirit and with fire! And it is interesting that John’s words were also in the context of the harvest, as he goes on to talk about the winnowing fork, the wheat and the chaff (Matthew 1:11-12). Jesus often described evangelism and the flourishing of the word of God in our lives in agricultural terms, using the metaphor of seeds and crops, harvest and harvesters. He said the fields were white and all that was needed was the harvesters. He was not wrong. Look what happened just 50 days after His resurrection:

Now there were dwelling in Jerusalem Jews, devout men from every nation under heaven. And at this sound the multitude came together, and they were bewildered, because each one was hearing them speak in his own language. And they were amazed and astonished, saying, “Are not all these who are speaking Galileans? And how is it that we hear, each of us in his own native language? Parthians and Medes and Elamites and residents of Mesopotamia, Judea and Cappadocia, Pontus and Asia, Phrygia and Pamphylia, Egypt and the parts of Libya belonging to Cyrene, and visitors from Rome, both Jews and proselytes, Cretans and Arabians—we hear them telling in our own tongues the mighty works of God.” And all were amazed and perplexed, saying to one another, “What does this mean?” (Acts 2:5-12)

Three thousand people came to faith that day! Peter stood up to address the crowd and enormous numbers of people from many nations believed in Jesus, right there and then. This was essentially the birth of the church. The gospel was for all nations, Jew and Gentile. The Holy Spirit was suddenly available to all people, men, women, slave and free. True fellowship with the God of Abraham, Isaac and Jacob was now possible for anyone who wanted to be include in the New Covenant with Israel, promised in Jeremiah 31:

“Behold, the days are coming, declares the Lord, when I will make a new covenant with the house of Israel and the house of Judah, not like the covenant that I made with their fathers on the day when I took them by the hand to bring them out of the land of Egypt, my covenant that they broke, though I was their husband, declares the Lord. For this is the covenant that I will make with the house of Israel after those days, declares the Lord: I will put my law within them, and I will write it on their hearts. And I will be their God, and they shall be my people. And no longer shall each one teach his neighbor and each his brother, saying, ‘Know the Lord,’ for they shall all know me, from the least of them to the greatest, declares the Lord. For I will forgive their iniquity, and I will remember their sin no more.” (Jeremiah 31:31-34)

The New Covenant (New Testament) was with Israel, but all nations were now invited to be grafted in! It was a bit of a culture shock at first, and it took some work getting used to, but suddenly, at Pentecost, the Feast of Shavuot, everything changed. The God of Israel opened up a new and living way for everyone to come to Him through that New Covenant in the Messiah’s blood and His Spirit could now be poured out on all flesh. Now, the Law could be written on our hearts! God’s Spirit could now indwell each and every believer, helping us to live His way.

Now the Lord is the Spirit, and where the Spirit of the Lord is, there is freedom. (2 Corinthians 3:17)

Read the full article: https://www.oneforisrael.org/holidays/biblical-feasts/spring-feasts/what-is-shavuot-countdown-to-pentecost/