Speak to the sons of Israel and say to them, "The LORD's appointed times which you shall proclaim as holy convocations—My appointed times are these." (Leviticus 23:2)
In Leviticus 23, God gives a calendar to His people. This biblical calendar is different from the one to which we are accustomed. The biblical calendar is lunar: It is based on the phases of the moon. The waxing and waning of the moon determines the day of the biblical month. The tiny sliver of the new moon always appears on the first day of the month; the full moon indicates the middle of the month; the disappearance of the moon indicates the end of the month.
God declares certain days to be mo'adim (מעדים); that is, "appointed times." He says, "The LORD's appointed times which you shall proclaim as holy convocations--My appointed times are these." (Leviticus 23:2)
What does this mean? Leviticus 23 is like God's day planner. He has made appointments on which to meet with His people. They include the weekly Sabbath, the Feasts of Passover and Pentecost, the Feast of Trumpets, the Day of Atonement and the Feast of Booths.
The Apostle Paul teaches that the festivals are like a shadow cast by Messiah. (Colossians 2:16-17) That means that each of God's appointed times should teach us something about Messiah.
Almost all of the appointed times commemorate some great past act of redemption. For example, the Feast of Unleavened Bread commemorates the exodus from Egypt.
But the biblical festivals can also be understood as an eschatological blueprint. In a sense, they lay out the pattern of redemption because they truly are God's appointed times for interacting with man. Each appointed time foreshadows one of the appointed times of God's plan of redemption. In that regard, they are the appointed times of Messiah. They are the "times [and] epochs which the Father has fixed by His own authority." (Acts 1:7) They represent the appointed time "of that day and hour no one knows, not even the angels of heaven, nor the Son, but the Father alone." (Matthew 24:36) To study the festivals is to study the future. To study the festivals is to study Messiah.
The appointed times communicate deep spiritual lessons to those who practice them. Every festival draws us closer to the living God and His holy Son.
The appointed times of the LORD are like annual rehearsals for the appointed times of redemption. They are like the blueprints for the work of Messiah. The spring festivals of Passover, Unleavened Bread, the Omer, and Pentecost all received a messianic fulfillment in the Master's first advent. The fall festivals of the Rosh Hashanah, the Day of Atonement, the Festival of Sukkot, and the Eighth Day all point toward His second coming. They are a "shadow of what is to come" (Colossians 2:17).