As the chart of Lev 8-10 reveals, the third panel (Lev 10) does not tell of Moses or Aaron offering sacrifices but instead says, “You are to distinguish between the holy and common, and between the unclean and the clean. And you are to teach the people of Israel all the statutes that YHWH has spoken to them by Moses” (Lev 10:10-11). Thus we can see a transition in Lev 8-10 from sacrifices (Lev 1-7) to distinguishing the unclean and the clean (Lev 11-16). The sacrifices (Lev 1-7), performed by the priests (Lev 8-10) were necessary to make many unclean things clean (Lev 11-16).
The chapter divisions in your English Bibles are helpful since each chapter covers a subject starting with “YHWH spoke to Moses.” Lev 11 deals with unclean animals. Lev 12 with the uncleanness of childbirth. Lev 13 with unclean skin and fungus diseases and Lev 14 with their cleansing. Lev 15 with unclean bodily discharges. And then finally Lev 16 addresses the day of atonement when the tabernacle itself is cleansed. The day of atonement was necessary because of Israel’s uncleannesses and their transgressions (Lev 16:16). Thus Wenham says, “chs. 11-15 provide essential background for understanding the significance of the day of atonement (16)” (161). He also noticed the connection with Lev 10:10.
There is a three-fold distinction of clean and unclean animals: Land, water, and sky animals. For land animals they could eat whatever parts the hoof, is cloven-footed, and chews the cud (Lev 11:3). Other land animals like the camel, rock badger, hare (each chews the cud but does not part the hoof) (Lev 11:4-6) and the pig (parts the hoof and is cloven-footed but does not chew the cud) (Lev 11:7) are unclean. The people were not to eat them, or touch their dead carcasses, because “they are unclean to you” (Lev 11:8).
For water animals, they could eat everything with fins and scales (Lev 11:9) but other water animals were “detestable to you” (Lev 11:10-12). And for the sky creatures, first are listed some “detestable” birds (Lev 11:13-19), then winged insects that go on all fours are said to be “detestable” (Lev 11:20) but then the next verse says there is an exception for those with jointed legs above their feet to hop on the ground (Lev 11:21) and lists those you could eat (Lev 11:22).
The rest of the chapter deals with the treatment of this uncleanness and mentions other animals that are unclean like mice and lizards. These regulations served to set Israel apart chosen from the nations as holy because YHWH is holy (Lev 11:44-45). This was symbolic for the division between holy Jews (represented by the chosen animals) and common Gentiles (represented by the animals that were not chosen). It is notable, as Wenham says, that animals were expected to keep Torah and those people or animals who drink blood or eat flesh without draining blood are unclean. Actually the law forbidding eating meat with the blood still in it predates Moses. Noah was told, “You shall not eat flesh with its life, that is, its blood” (Gen 9:4), which may explain why the apostles kept this prohibition (Acts 21:25). But nevertheless, the animals were set apart of God’s election.
And even this verse in Gen 9 is not the first time that people were forbidden to eat certain things: Adam and Eve were forbidden to eat from one tree, though it is interesting that there are no unclean plants in Leviticus. However, the seriousness of the uncleanness for the people of Israel was relatively little since all that was required for cleansing when one came into contact with a dead carcass of an unclean animal was washing and waiting until evening. And the distinction between clean and unclean animals is abolished in the New Testament because the distinction between Jews and Gentiles is abolished in Christ.
Lev 12 is much shorter, but more serious since it includes sacrifices as part of the cleansing. Here we are looking at the uncleanness of childbirth. The numbers are significant: unclean and contagiously so for seven days for a boy (Lev 12:2) and fourteen days for a girl (Lev 12:5). She must stay at home for 33 days for a boy (Lev 12:4) and 66 days for a girl (Lev 12:5). Thus a total of 40 days for a boy and 80 days for a girl (traditional period of testing is 40 days or multiples thereof). The boy is circumcised on the eighth day (Lev 12:3). Circumcision is the sign of the covenant and failure to do it would cut off that son from his people. The offerings are to make atonement for her and to purify her from the discharge of blood (Lev 12:6-8). It has been suggested that we remember the increased pain of childbirth was a reminder of the curse due to original sin. Wenham notes that the structure of a period of uncleanness, sacrifice, summary, and provision for the poor reappears in other chapters in Leviticus (186).
Lev 13-14 deal with skin diseases. It may be that because these diseases are visible that they are singled out for ceremonial uncleanness. All diseases remind us of death and thus have something in common with issues of blood (blood symbolizing life). The skin diseases are classified based on what they look like on the outside. And periods of seven days are common to see if it gets better or worse to make a diagnosis. The priest, as a servant of the Lord, has declarative power here — he declares if the person is clean or unclean based on the criteria in Scripture. The cleansing is more difficult, when it is possible, for such diseases. And these sacrifices are for atonement. And they prepare us for Jesus who cleanses many and the priests then are forced to declare them clean and then Jesus offers Himself up as a sacrifice for atonement of sin.
Lev 15 deals with unclean discharges first from men. The one who has a discharge waits seven days for his cleansing and washes his clothes and bathes his body (Lev 15:13). And on the eighth day he offers sacrifices (Lev 15:14). An emission of semen makes the man unclean until evening and he has to bathe his body (Lev 15:16). The chapter transitions to women by mentioning the case of a man who does so while laying with a woman (Lev 15:18). The next verse (Lev 15:19) discusses how menstrual impurity lasts for seven days and later verses deal also with situations where blood issues may last longer (Lev 15:25). The purpose statement is then given about defiling the tabernacle (Lev 15:31).
Lev 16 addresses the day of atonement. Given the atonement sacrifices of many of the previous chapters, we can see the need for a day of atonement. These are themes that seem odd to modern ears but ones that are consistent in the Old Testament. The themes run throughout Ezekiel, especially for our purposes in Ezek 44:23. The prophet Ezekiel even compares Israel’s ways and deeds to the uncleanness of a woman in her menstrual impurity (Ezek 36:17) — a comment that only makes sense given these chapters in Leviticus. He also mentions this particular impurity elsewhere (Ezek 18:6, 22:10). And the prophet is concerned with this issue of uncleanness so much that it appears repeatedly like when God says, “I will sprinkle clean water on you, and you shall be clean from all your uncleannesses, and from all your idols I will cleanse you” (Ezek 36:25). So there is a need for a more permanent removal of these uncleannesses than a single day of atonement each year could provide.
Aaron had to offer atonement for himself and his house first and then he could do so for the nation. The reason to “make atonement for the Holy Place” was “because of the uncleannesses of the people of Israel and because of their transgressions, all their sins. And so he shall do for the tent of meeting, which dwells with them in the midst of their uncleannesses” (Lev 16:16). One goat Aaron would put his hands on its head and “confess over it all the iniquities of the people of Israel, and all their transgressions, all their sins. And he shall put them on the head of the goat and send it away into the wilderness” (Lev 16:21). This takes place on the tenth day of the seventh month (Lev 16:29).