God commanded Israel to observe Passover, Unleavened Bread, Firstfruits, Seventh Days, Feast of Trumpets, Day of Atonement, and Feast of Tabernacles, which were types and shadows of what Jesus would do. The seven feasts consisted of three periods: The first period consisted of Passover and Unleavened Bread; the second period consisted of the Feast of Firstfruits and the Feast of Seventy Days (Pentecost); and the third period consisted of the Feast of Trumpets, the Day of Atonement, and the Feast of Tabernacles.

Passover commemorates the deliverance from Egypt, Unleavened Bread commemorates Israel's suffering, Sukkot commemorates the crossing of the Red Sea, and Sukkot commemorates the ascent of the mountain to receive the first Ten Commandments. The Feast of Trumpets commemorates the blowing of the trumpet of repentance to receive the second commandment, the Day of Atonement commemorates the receiving of the second Ten Commandments, and Sukkot commemorates the gathering of materials for the building of the Temple. 

All of these feasts were observed in the temple, and each had its own unique way of proceeding. Passover was observed by killing a year-old male lamb and eating its meat, and the Feast of Unleavened Bread was observed by eating unleavened bread and bitter herbs for seven days. The Feast of Firstfruits was observed by offering to God the first ripe fruits of the grain; the Feast of Weeks was observed by offering to God the sheaves of the harvest; the Feast of Trumpets was observed by proclaiming repentance with a long blast of the trumpet; the Day of Atonement was observed by the high priest entering the holy of holies and handing over all the sins to Azazel to purify the temple; and the Feast of Tabernacles was observed by cutting down branches of trees from the mountains and building a tabernacle of them and dwelling in it; these were the regulations for keeping the feasts.

However, these feasts were types and shadows of what Jesus would accomplish. Jesus fulfilled the prophecy with seven feasts in three tiers, in this order

1) The Feasts of the First Period (Passover and Unleavened Bread)

Jesus was sacrificed on the cross at 3 p.m. on January 14 of the Jewish calendar, the day the Passover lamb was sacrificed. Having freed spiritual Israel from the sinfulness of Egypt, Jesus was laid in the tomb. This event caused the disciples to tremble in fear, which is the fulfillment of the prophecy of Passover and Unleavened Bread that occurred in the days of Moses.

2) Feasts of the Second Period (Feast of Firstfruits and Seventy Days)

Jesus fulfilled the prophecy of the Feast of Firstfruits by rising from the dead as the first ripe fruit (1 Corinthians 15:20). The Bible likens fruit to saints, so when Jesus rose from the dead and went to God, he fulfilled the prophecy of offering the first fruits on the Feast of Firstfruits. And after Jesus' resurrection, the dead saints in the graves rose from the dead and came to God, which fulfilled the prophecy of Pentecost. (Matthew 27:50-53) Because Pentecost is a day of offering the harvest, the prophecy of Pentecost was fulfilled by the resurrection of many saints, who are described as fruit.

3) Feasts of the Third Period (Feast of Trumpets, Day of Atonement, and Feast of Tabernacles)

The resurrected Jesus ascended into heaven on the 40th day after his resurrection, and before he ascended, he told his disciples not to leave Jerusalem because he would give them the Holy Spirit in 10 days. So the disciples gathered their hearts and purified themselves in prayer. The Holy Spirit is given to those who repent (Isaiah 59:20), and by saying this 10 days before, Jesus caused the trumpet of repentance to be blown. Jesus' ascension to heaven fulfilled the prophecy of the Feast of Trumpets, when the trumpet of repentance would be blown. Jesus' ascension to heaven fulfilled the prophecy of the High Priest entering the Holy of Holies on the Day of Atonement. Since the earthly temple is a type and shadow of the heavenly temple, the actual Holy of Holies is in heaven. Therefore, Jesus' resurrection and subsequent ascension into heaven as High Priest of the heavenly temple fulfilled the prophecy of the High Priest entering the Holy of Holies. After his ascension, Jesus cast Satan out of heaven to earth, which fulfilled the prophecy of the Day of Atonement when he would lay hands on the goat of Asher and cast all sins into the wilderness. (Revelation 12:7-9)

Jesus then came upon the bodies of the saints by the Holy Spirit, giving them knowledge of God's will and putting the Word into their hearts. Just as Israel received the Word of God through the Ten Commandments, so the saints received the Word of God through the Holy Spirit, so the prophecy of the Day of Atonement was fulfilled when the Holy Spirit came upon the saints. The prophecy of the Feast of Tabernacles was also fulfilled because the saints, having received the Holy Spirit, became the temple of God where the Holy Spirit was present.

Just as Israel, having completed the Day of Atonement, cut down trees from the mountain to build a tabernacle (sanctuary) and dwelt in it, so Jesus, in accordance with the prophecy of the Day of Atonement, cast out Satan from heaven, and by the Holy Spirit came into the bodies of the saints, inscribed the word of God (the Ten Commandments) on them, and made their bodies a temple in which He dwells, so that the prophecies of the Day of Atonement and the Feast of Tabernacles were fulfilled together (1 Corinthians 3:16).

In this way, Jesus fulfilled all the prophecies in the order of the feasts. God's people who believe in Jesus do not need to keep sacrifices for sin again because all the feasts for the forgiveness of sins have been fulfilled. Forcing people to keep sacrifices for the forgiveness of sins, such as the Day of Atonement, is a deception by Satan. Satan will trick people into keeping the Day of Atonement by telling them that it is a new Day of Atonement.