Then he shall slaughter the people's sin-offering goat, and bringing its blood inside the veil, he shall do with it as he did with the bullock's blood, sprinkling it on the propitiatory and before it. ~Leviticus 16:15
Yom Kippur begins, this year, at sundown on September 21st. This Day of Atonement, as prescribed in Leviticus and Numbers, has a very special, exceedingly significant meaning for Christians as we look back to the roots of our faith to understand how Christ fulfilled, and continues to fulfill, our need for propitiation. Essentially, "propitiation" means to appease the wrath of God or to turn it away. Yom Kippur, then, was the day in which God's people were able to atone for their sins through the sacrifices made, on their behalf, by the high priest. In the book of Leviticus, this responsibility fell upon Aaron's shoulders and God provided very specific details on how the entire sacrificial process was to be carried out; from the requirement of the priest's ritual cleansing bath, to what the priest was to wear, to how and what the priest was to sacrifice. Yom Kippur was evidence, and continues to be, that there are two very real aspects of God: mercy and justice.
The Day of Atonement has four major components: holy convocation (Num. 29:7); prayer and fasting (Lev. 23:27-29); offerings (Lev. 16); and a refrain from labor (Lev. 23:32). As Christians, we are able to look at these aspects of Yom Kippur and see how we are also called to the occasion. Whether gathered as a community in which we proclaim our faith through the Nicene Creed and accept the body of Christ through Communion, or during our own focused prayers and fasting on Good Friday, we are able to connect ourselves with God's call upon us as we accept atonement given through Christ's blood.
Yom Kippur reminds us that Christ became, at once, the high priest, the blood, and the propitiation (or what is often called the "Mercy Seat"). He who knew no sin took on our sin; He became our "scapegoat." We know Him to be — as we hear proclaimed in Mass — a priest forever, in the line of Melchizedek. His was the blood that the Father knew would be shed for our sins and the sins of all mankind. Christ acquired the Church through His own blood (Acts 20:28) when, as the Mercy Seat, He appeased God's wrath, turning it away so that, through Him, we might be able to approach the Father. It is during Yom Kippur that God's people would call out to be written in the book of life. As Christians, we know that by God's grace and mercy, given through His Son's most precious blood, our names are written in the book of life and yet we are also reminded throughout Scripture of God's judgment (1 Cor. 11:32, Romans 2:5-8). But ours is a loving Judge. The very act of the Son becoming high priest, blood, and propitiation for us reveals the Father as both merciful and just.
Contrary to what our secular world teaches, we cannot save ourselves; we cannot redeem mankind, but instead are called to be holy as our Creator is holy. In that holiness we become merciful and kind to one another, witnessing in our words and actions the salvation available through Christ, and knowing that we serve a righteous and sovereign God. May we, as Yom Kippur approaches, renew within our hearts the depths of gratitude for the beauty of His Precious Blood that makes atonement for us.