The Law of Sin Offerings
If a priest sins unintentionally but comes to realize his sin. He is to bring a bull without defect before the Lord. He shall lay his hand on the head of the bull and slaughter it just like in the law of burnt offerings and peace offerings. However, this time, the priest takes some of the blood into the tent of meeting and sprinkles the blood with his finger seven times in front of the veil. Beyond the veil is the mercy seat and the ark which contains the convent testimony. The priest is also to put some of the blood on the horns of the altar. All of the fat, the kidneys and the liver are removed just like in the peace offering. They are offered up to the Lord in smoke on the altar. In the peace offering the meat was eaten by the congregation but with sin offerings the meat and hide are taken outside the camp where the ashes are poured out from the altar and it is burned there. Once atonement is made he will be forgiven.
If the whole congregation sins unintentionally but comes to realize their error, then the elders of the congregation are to be their representatives in bringing a bull before the tent of meeting. The elders are to lay their hands on the bull when it is slaughtered. The priest is to do the same things with the blood and fat and hide that he did for the individual who sinned. Once atonement has been made for the congregation, they will be forgiven.
When a leader sins unintentionally but comes to realize his error, then he is to bring a male goat without defect before the Lord. He is to lay his hand on the male goats head and slay it before the Lord. The priest is to put some of the blood on the horns of the altar and pore the remainder out at the base of the altar. All of the fat is offered up in smoke to the Lord on the altar. After the atonement he will be forgiven.
If a common person sins unintentionally but comes to realize his error, he is to bring a female goat or a female lamb without defect before the Lord. He is to lay his hand on the female goats head while it is slayed. The priest dips his finger into the blood and puts some on the horns of the altar but pores the remainder out at the base of the altar. The fat of the sacrifice is removed and offered up in smoke on the altar. After the atonement he will be forgiven.
It seems that there is a progression in offense based on position. Priest, congregation, leader and common person. For the priest and the congregation, the blood of the offering is taken into the tent of meeting but for the leader and the common person it is not. So, it appears that the offense was greater for a priest than a common person. However, if it is the whole congregation, then it was considered equally offensive. Nonetheless, all sin must be atoned. God cannot turn a blind eye to sin. Sin always results in death but the Lord excepts a sacrifice in place of the person who sinned. In atonement, sin guilt was transferred to the animal. The animal was then treated as if it had sinned. Therefore, guilt is removed from the person. The person is then treated as if he never sinned. This is the way that Christians should understand the atonement of Jesus Christ.
He made Him who knew no sin to be sin on our behalf, so that we might become the righteousness of God in Him. (2 Corinthians 5:21, NASB)