"Atonement has incomparably the deepest place of all truths in scripture, save only Christ's person." (W. K., Lectures on the Pentateuch, p. 275.)
In this truly wonderful and comprehensive chapter 16 of Leviticus we get the most profound truth of propitiation Godward, typifying that great work of Christ on the cross. Only on this notable tenth day of the seventh month could Aaron enter into God's presence within the vail. For this God specified that he come "with a young bullock for a sin offering and a ram for a burnt offering." Also he was to bathe, be attired entirely with holy linen garments, have a censer full of burning coals of fire from off the brazen altar, have sweet incense to "put on the fire before the Lord, that the cloud of incense may cover the mercy seat", where he was to sprinkle the blood of the bullock to make "atonement for himself and for his house" to propitiate God for sin.
Incidentally here, although typically important, Aaron's house represents the Christian family of priests, 1 Peter 2:5-9; Rev. 1:6. Aaron's acceptance in God's presence, by virtue of the blood, tells us of our being "accepted in the Beloved" (Eph. 1:6) and our present priestly privileges of entering by faith as worshipers into the holiest (Heb. 10:19).
During this present age, Israel's Messiah and Great High Priest is hidden, as it were, within the vail of the sanctuary until He comes forth for their blessings.