In Leviticus 10, we learn about the death of Nadab and Abihu, Aaron's sons who didn't follow the commands of the Lord. They offered unauthorized fire before the Lord, and the fire came out from the presence of the Lord and consumed them. "All the house of Israel may mourn for those the Lord destroyed by fire." The Lord said to Aaron, "You must distinguish between the holy and the common, between the unclean and the clean, and you must teach the Israelites all the decrees the Lord has given them through Moses."

Leviticus 8 & 9 are about the ordination of Aaron and his sons as priests and the beginning of their ministry. The Lord directed Moses to bring Aaron and his sons before the Tabernacle and gather the people, and then the Lord commanded Moses to wash them with water and dress them with the holy garments. Aaron was dressed with a tunic, sash, ephod, breastpiece, Urim and Thummim, turban, diadem, etc. The sons of Aaron were dressed similarly and they all were consecrated with anointing oil. Then they performed the sin offering, the burnt offering, and a ram was slaughtered for the ordination also. Moses said, "What has been done today was commanded by the Lord to make atonement for you... and Aaron and his sons did everything the Lord commanded through Moses". They came with the entire assembly near the Tabernacle and stood before the Lord and Moses said, "This is what the Lord has commanded you to do, so that the glory of the Lord may appear to you." Moses then instructed the priests how to make the offerings as atonement for themselves and the people. "Then Aaron lifted his hands toward the people and blessed them... Moses and Aaron then went into the Tent of Meeting and when they came out, the glory of the Lord appeared to all the people. Fire came out from the presence of the Lord and consumed the offerings and the fat portions on the alter and when all the people saw it, they shouted for joy and fell facedown."

Leviticus 7 concludes the instructions for the offerings, including the guilt offering and peace offerings. "The Lord gave these instructions to Moses on Mount Sinai when he commanded the Israelites to bring their offerings to the Lord in the wilderness of Sinai." The process of the various offerings teaches about the seriousness of sin, the importance of confessing and repenting of our sins, and bringing them to God for forgiveness.

Leviticus 6 "If anyone sins and is unfaithful to the LORD by deceiving his neighbor about something entrusted to him or left in his care or stolen, or if he cheats him, or if he finds lost property and lies about it, or if he swears falsely, or if he commits any such sin that people may do- when he thus sins and becomes guilty, he must return what he has stolen or taken by extortion, or what was entrusted to him, or the lost property he found, or whatever it was he swore falsely about. He must make restitution in full, add a fifth of the value to it and give it all to the owner on the day he presents his guilt offering. And as a penalty he must bring to the priest, that is, to the LORD, his guilt offering, a ram from the flock, one without defect and of the proper value. In this way the priest will make atonement for him before the LORD, and he will be forgiven for any of these things he did that made him guilty."

Leviticus 5 describes more situations when someone would be guilty of sin, requiring a sin offering. Whether or not something sinful was done knowingly, admission of guilt was required once you realized the foolishness of what was done. When a person became aware, he must confess his sin and bring an animal sacrifice as the penalty for such sin, in order to be made right with the Lord and receive forgiveness.

Leviticus 4 gives the details for "sin offerings" that God prescribed to the Israelites for unintentional sin, not that of outright rebellion against God. So there were procedures also in these instances for bringing bulls, goats, or sheep to the Tabernacle to be presented to the Lord as sacrifices and the priest would "make an atonement for them and they would be forgiven".

Leviticus 3:16 (NIV) All the fat is the Lord's.