Without the shedding of blood there is no forgiveness of sins (Hebrews 9:22), and Leviticus 4 lays out the sin offering, or purification offering, that pictures that necessity in detail. Its primary purpose was to cleanse the sanctuary from the pollution of sin, restoring the people to fellowship after a ceremonial offense so that God’s presence could continue dwelling among them.
The law distinguishes unintentional sins, committed in ignorance, from presumptuous, high-handed sin, and prescribes specific offerings depending on who sinned, priest, whole congregation, leader, or common person, a pattern echoed in David’s own prayer to be kept back from presumptuous sins and the great transgression they bring (Psalm 19:13). All of this points forward to Christ, whose own blood accomplished the atonement these repeated animal sacrifices could only foreshadow.