Concise Bible Dictionary:
This was one of the most solemn days in the whole year, being, in common with the Sabbath, the only occasion on which the people were commanded to cease from work entirely. On the day of atonement they were also to afflict their souls, and that by a statute forever (Lev. 16:29-31). The time of the year in which the day fell — the tenth day of the seventh month — is very significant, especially when viewed in connection with the other feasts. See FEASTS.
The rites prescribed for the Day of Atonement are given (Lev. 16; Lev. 23:26-32; Num. 29:7-11). In the first we have a detailed account of the peculiar work appointed for the high priest on that day; in the second, we learn what had been shortly expressed in Leviticus 17, how the people should comport themselves on that day; and in the third we are told of certain sacrifices which were to be offered up besides those spoken of in Leviticus 16. In this passage we learn that the Day of Atonement was a gracious provision in order that the relationship of the people with the holy God who dwelt among them might be maintained.
The points to be noticed are
1. The entrance into the holy place. Aaron, on account of the failure of his sons in the priestly office, could not enter there at all times, but, as the representative of the people, once a year on the Day of Atonement, and he must enter alone. Even then he went in not for communion, but for the cleansing of the defilements of a people among whom God dwelt. He must put on the holy linen garments, and must enter with a cloud of incense and with blood, lest he die. For the contrast to this for the Christian (see Heb. 9:7-12).
2. Aaron must offer sacrifices for himself and his house; a young bullock for a sin offering and a ram for a burnt offering. Aaron and his sons represent the saints who now form the church as a company of priests, and were thus, in the type, distinct from the people (Israel) as an earthly company who formed the camp.
3. For the congregation two goats were taken for a sin offering, and a ram for a burnt offering. On the two goats the lot was cast, and the one on whom the lot fell was for Jehovah, and was offered as a sin offering. This, as with the bullock for Aaron and his house, was the atonement offering Godward. The other, after being presented before the Lord, was brought forth: on him Aaron laid both his hands and confessed over him “all the iniquities of the children of Israel and all their transgressions in all their sins, putting them upon the head of the goat,” (Lev. 16:21), which was then sent away into the wilderness, a land of forgetfulness. In the two goats we have the two sides of atonement, namely, that which meets the character and holiness of God, and that which meets the need of the sinner as to the removal of his sins. (See ATONEMENT.)
4. Atonement was made for the holy place, for the tabernacle, and for the altar, because of the uncleanness of the children of Israel.
The day of Atonement being once a year — once every year, by a perpetual statute — stands in strong contrast to the one perfect sacrifice of the Lord Jesus, by which the believer is perfected in perpetuity. (See Heb. 10:1-18).
The reiterated injunction to afflict their souls in connection with this great day has an important prophetical bearing as to the Lord’s earthly people Israel. If the blowing of trumpets on the first day of the seventh month suggests that testimony from the Lord which shall arouse the nation from their long spiritual slumber, the Day of Atonement points to the moral effect produced in them when they shall look upon Him whom they have pierced, and mourn for Him. They will also at this time learn and confess that He was wounded for their transgressions (Zech. 12:10-14; Isa. 53; Psa. 51).
From Manners and Customs of the Bible:
Leviticus 16:34. This shall be an everlasting statute unto you, to make an atonement for the children of Israel for all their sins once a year.
The Great Day of Atonement took place on the tenth day of the seventh month, Tisri, corresponding to our October. It was a day of great solemnity, especially designated and kept as a fast day (see Lev. 23:27; Num. 29:7; compare Psa. 35:13; Isa. 58:5) and in later times was known by the name of The Fast. Acts 27:9. On this day the high priest, clad in plain white linen garments, brought for himself a young bullock for a sin offering and a ram for a burnt offering; and for the people two young goats for a sin offering, and a ram for a burnt offering. The two goats were brought before the door of the Tabernacle, and by the casting of lots one was designated for sacrifice and the other for a scapegoat. The high priest then slaughtered the bullock and made a sin offering for himself and family. He next entered the Most Holy Place for the first time, bearing a censer with burning coals, with which he filled the place with incense. Taking the blood of the slain bullock, he entered the Most Holy Place the second time, and there sprinkled the blood before the mercy-seat. He next killed the goat which was for the people’s sin offering, and, entering the Most Holy Place the third time, sprinkled its blood as he had sprinkled that of the bullock. Some of the blood of the two animals was then put on the horns of the altar of incense, and sprinkled on the altar itself. After this the high priest, putting his hands on the head of the scapegoat, confessed the sins of the people, and then sent him off into the wilderness. He then washed himself, and changed his garments, arraying himself in the beautiful robes of his high office, and offered the two rains as burnt offerings for himself and for the people (Lev. 16).