The Torah has a lot of rules; 613, in fact, if you follow the count of the medieval Jewish scholar Maimonides. Depending on who's counting, 246 or 247 of them are in Leviticus.
What is an Israelite supposed to do after breaking these rules? Present a sacrificial offering, of course!
With so many rules to keep in mind—not to mention their complex explanations over centuries of rabbinical debate—the Israelites can't help but break a few by accident, and maybe they're not even sure if what they've done breaks any laws. What are otherwise faithful followers to do?
No problem—Leviticus has them, ahem, covered.
The focus of chapter four is the sin offering, which is the offering that priests make as atonement for sins committed in ignorance.
The first words of the chapter are, "And the Lord spoke unto Moses," a sign that the book is moving on to a new subject.
The offerings in chapters 1-3 are voluntary. The offerings described here and in the next chapter have to be done after Israelites have done something wrong. Or after they didn't think they did anything wrong but found out they actually did. Or after they think they might have done something wrong. You get the point.
As anyone around during the summer of 1153 BCE remembers, the official chant for the sin offering is the irresistibly catchy Sin? Me? Maybe.
The Altar of Dorian Gray
The rules for making the sin offering get rather fancy.
Some people think the sacrifice was cooked up (ouch!) some time after the much simpler offerings in the first three chapters.
One highlight: the priest dips his finger in blood and sprinkles it seven times in front of the entrance to the Tabernacle.
Another reason for the Cullen family to take a time machine back to the 5th century BCE: the priest pours the animal's blood on the base of the sacrificial altar in the Tabernacle courtyard and the altar of incense inside.
God gives rules for several types of sin offerings, including rituals on behalf of ordinary people, rulers, and all the people of Israel.
Laying hands on the head of the animal being offered for atonement pops up again, too.
This chapter introduces yet another issue that comes up again and again: if you take any actions that aren't in keeping with the way things are supposed to be, you can pollute the Tabernacle itself.
Leading Leviticus scholar Jacob Milgrom calls this "the priestly Portrait of Dorian Gray" (source). In this Oscar Wilde novel, a corrupt young man stays good-looking while his portrait gets more ugly.
Speaking of which, isn't it ironic that Wilde inspired one of the most influential images for understanding sin and atonement in Leviticus?