As many students of the word of God know, there are three main feasts or holidays in scripture.
1. Passover – Where a lamb was killed and his blood paid for the people’s sin for the year.
Jesus Christ is the Passover Lamb God gave mankind. Hebrews 9:25-28 KJV “Nor yet that he should offer himself often, as the high priest entereth into the holy place every year with blood of others;
 For then must he often have suffered since the foundation of the world: but now once in the end of the world hath he appeared to put away sin by the sacrifice of himself.
 And as it is appointed unto men once to die, but after this the judgment:
 So Christ was once offered to bear the sins of many; and unto them that look for him shall he appear the second time without sin unto salvation.
2. Shavuot – Pentacost – You can read this in Leviticus 23:15-17. The two loaves representing Jews and Gentiles.
The Old Testament Shavuot poured out God’s word the New Testament Shavuot poured out the Holy Spirit in Acts 2.
Because on Shavuot an offering of the first fruits was made and Jesus is the firstfruit of the resurrection when the Holy Spirit was poured out in Acts 2 the church made up of Jew and Gentile is a type of firstfruits.
Shavuot / Pentecost today we now have the Holy Spirit. But we celebrate because God poured out the Holy Spirit, we remember the cost or price Jesus paid for us and we look for a great work of the Holy Spirit and look for more from the Holy Spirit on Shavuot / Pentecost.
In the Old Testament the Holy Spirit would come and go but in the New Testament, when God poured out the Holy Spirit on Shavuot / Pentecost, the Holy Spirit in dwells all true believers. When the church is removed from the earth as I Thessalonians 4:13-18 speak of, then the Holy Spirit is removed too. As we see from scripture the Holy Spirit will come and go during the tribulation, just like he did in the Old Testament.
Pentecost is 50 days from Passover. Always.
3. Tabernacles – Also called the Feast of Harvest and is in the fall. Leviticus 23:34-43 a time of celebration and thanksgiving.
So friends, Shavuot in America is Saturday June 11 and June 12. Some people give a special offering to God on Shavuot / Pentecost but whatever you choose to do to celebrate Shavuot, may you ask God to make the Holy Spirit real to you and confirm your salvation.