Much of the Bible discusses the idea of atonement. What is it? Why is it important? I admit it is a topic that is difficult for me to fully understand as addressed in the Old Testament because there are so many rules and regulations.
The book of Leviticus spends a good portion discussing offerings for atonement. It explains the role of sacrifice in God's plan. There are laws for burnt offerings of livestock such as bulls, sheep, or goats, laws for what to do with the meat of the offered animals, laws for how to use birds like pigeons for burnt offerings, laws for grain offerings, laws for peace offerings, laws for sin offerings, laws for guilt offerings, and the roles of the priests in all these offerings for atonement.
So many laws to remember. It is a good thing that God chose the tribe of Levi to organize as a priesthood to help the citizens make their offerings for atonement.