Seventh Day Sabbath
The seventh day Sabbath is a gift that God has given to man. God was the first Sabbath Keeper, setting the standard for us to follow. It was certainly not out of necessity that God rested; he did not require regeneration as we do. We require not only a weekly regeneration but one every night. Rest here implies a cessation of work because of completion. He did it in order to hollow the day and set example. By his resting, only on this day, he set it aside from every other day.
Passover & the Feast of Unleavened Bread
This feast signifies the basic component that all our religious substance is founded upon. That is that “Jesus Saves”. We have no relationship with God if he does not first free us from our other master (satan). The two God ordained memorials in the feast commemorate the great ability of God to deliver his chosen out of any ordeal. He is both the power shown in the blood covering and the means shown in his mighty hand.
There is great significance in the blood relationship to the feast. The lamb's blood placed on the door post was the sign the destroyer looked for and he passed over those houses. God is still looking for the blood, not on the door post, but the blood that Jesus shed that covers your sins. Death will pass over you, if you have been washed in and covered by the blood of Jesus Christ.
The second of the three annual festivals was Pentecost, also called the Feast of Weeks, the Feast of Harvest, and the day of first fruits. It was celebrated seven complete weeks, or fifty days, after the Feast of Unleavened Bread; therefore, it was given the name Pentecost.
Essentially a harvest celebration, the term "weeks" was used of the period of grain harvest from the barley harvest to the wheat harvest, a period of about seven weeks. It was celebrated as a Sabbath with rest from ordinary labors and the calling of a holy convocation. It was a feast of joy and thanksgiving for the completion of the harvest season. It is the memorial of God giving of the law at Sinai. God confirmed it when He gave the initial outpouring of the Holy Ghost and wrote the law in the hearts of men.
Feast of Trumpets
Modern Rosh Hashanah is traced back to the so-called "Feast of Trumpets," and the sounding of the trumpets on the first day of the seventh month (Ethanim or Tishri) of the religious calendar year. It is the memorial of the giving of the law on Pentecost and reminds us to be conscious of the law as we start the seasoning of ingathering; a time to look forward to the Lord’s return. The trumpet referred to here was the shofar, a ram's horn. It was distinctive from the silver trumpets blown on the other new moons. Silver trumpets were sounded at the daily burnt offering and at the beginning of each new month, but the shofar specifically was blown on the beginning of the month Tishri. It begins the "ten days of awe" before the day of atonement.
Day of Atonement
The only fast day stipulated in the law was the annual Day of Atonement (Yom Kippur), observed on the tenth day of Tishri (Ethanim). The Day of Atonement was the only day of the year that the priest entered the holy of holies to make sin offerings for himself, his family, and the "assembly of Israel."
Atonement, meaning reconciliation, was associated with sacrificial offerings to remove the effects of sin and in the New Testament, refers specifically to the reconciliation between God and humanity effected by the death, burial, and resurrection of Christ.
Atonement refers to the process God established whereby humans could make an offering to God to restore fellowship with God. Such offerings, including both live and dead animals, incense, and money, were required to remove the bad effects of human sin. We celebrate that Jesus has become the offering for our sins.
Feast of Tabernacles
Also called the feast of ingathering. Its observance combined the ingathering of the labor of the field, the fruit of the earth, the ingathering of the threshing floor and winepress, and the dwelling in booths (or "tabernacles"), which were to be joyful reminders to Israel. The "booth" in scripture is not an image of privation and misery, but of protection, preservation, and shelter from heat and storm. The feast began on the fifteenth day of Tishri (the seventh month), which was five days after the Day of Atonement. It lasted for seven days. Our greatest hope is that Jesus will return and take us away to live with him forever. This feast celebrates that great harvest of the saints.