"For on that day shall the priest make an atonement for you, to cleanse you, that ye may be clean from all your sins before the LORD" (Leviticus 16:30).
It is generally known that the Jewish calendar follows the so-called lunar year, which is shorter than the solar year by almost eleven days. To correct this to correspond to the standard year, every third Jewish year has an extra month. This means that special days such as Yom Kippur happen at a different regular calendar date every year. This year it falls on this particular date.
The specified Biblical date for Yom Kippur is "on the tenth day of this seventh month" (Leviticus 23:27)—that is ten days after the feast of trumpets (see the devotional study for September 16 in this issue of Days of Praise). The ten days (including the two "holidays") are supposed to be days of repentance, confession, atonement, and forgiveness (Yom Kippur means "Day of Atonement").
The "atonement" (literally, "covering") was made by the high priest sacrificing one goat on the altar as a sin offering for the people, then sending another goat off into the wilderness; symbolically this "scapegoat" carried "all their iniquities unto a land not inhabited" (Leviticus 16:22), so they need be remembered no more. First, of course, the other goat must have shed his blood to pay for those sins, for "without shedding of blood is no remission" (Hebrews 9:22).
But all of this provided merely a temporary "covering." Both goats were actually a type of the coming "Lamb of God, which taketh away the sin of the world" (John 1:29). He could only take them away, of course, after He had first "put away sin by the sacrifice of Himself" (Hebrews 9:26).
For those who appropriate this amazing gift of God through Christ, God can promise "their sins and iniquities will I remember no more" (Hebrews 10:17). HMM