The major theme of Leviticus is worship. Moses introduced this theme in the later chapters of Exodus, but he developed it more fully in Leviticus.
The book reveals how sinful Israelites could have a relationship with the holy God who dwelt among them. It also reveals how they could maintain that relationship and express it through worship.
One of the major revelations in Leviticus is the nature of sin. God took the fact that man is a sinner for granted in Leviticus. He established this in Genesis and Exodus. He clarified the nature of man's sinfulness in Leviticus. Sin has a three-fold character.
1. Sin is unlikeness to God. In the Creation we see man made in the image of God, but in the Fall we begin to see man's unlikeness to God. The whole system of worship in Leviticus teaches this truth. God is different from man ethically and morally. The word holy (Heb. kodesh) occurs over 150 times in Leviticus, more than in any other book of the Bible. The word occurs even in the sections of the book dealing with personal hygiene. Holy means pure, unblemished, clean, blameless. The opposite of holy is sinful. It is in contrast with God's holiness that we can understand man's sinfulness. Leviticus reveals the standards by which sinful people could have fellowship with a holy God. These standards and regulations point out the vast difference between the character of man and the character of God. God sees us as His Son as Christians (i.e., "in Christ").
2. Sin is essentially wrong that man does to God. To have a relationship with God, the wrong the redeemed sinner had done to God had to be atoned for. The Israelite did this wrong daily. It was the natural fruit of his sinful nature. Consequently he had to make payment for his sin periodically to God (monthly, seasonally, and yearly). God specified how the sinners were to pay for the wrong done Him, namely, by the offerings and sacrifices specified in the law. In Leviticus we learn that wrong done to another human being is wrong done to God. People belong to God, God gives them their lives in trust, and they bear God's image. When one person violates the basic rights of another, he has wronged not only that person but God too (cf. Gen. 39:9; Ps. 51:4). We too sin daily, but "Jesus paid it all."We could never compensate God adequately for the wrong we do to Him by sinning.
3. Sin results in distance from God. Because man is unlike God in his character, he is separate from God in his experience. The Israelites could not approach God except as God made a way and brought them near to Himself. The levitical system of worship illustrated the distance between man and God due to sin and the need for some provision to bring man back to God. The veil, the curtains, and the priests separated the ordinary Israelite from God. He doubtless sensed his personal separation from God as he participated in worship. Jesus tore the veil in two and opened access to God for us. After the Fall, Adam and Eve hid from God.
Another major revelation in Leviticus is the nature of atonement. Atonement is, of course, the solution to the problems that sin creates. Atonement means satisfaction. God covered the sins of the Israelites until a final, acceptable sacrifice would remove them completely. Old Testament saints obtained salvation on credit. (Ill. of a credit card) Through atonement man who is a sinner could enter into fellowship with God. Three things had to be present to make atonement for sin.
1. There had to be substitution. Every animal sacrifice in Israel involved the substitution of one life for another. A living being had to stand in the sinner's place and take the punishment for his sin. The substitute had to be sinless. Every sacrifice of an animal involved the death of an innocent substitute. Animals do not sin. They are not morally responsible.
2. There had to be imputation. God transferred the guilt of the sinner to his substitute when the sinner personally identified with his substitute by laying his hands on it. This ritual illustrated the transference of guilt for the Israelites.
3. There had to be death. Finally the substitute to which God had imputed guilt had to die. Atonement could not take place without death. The shedding of blood illustrated death. Blood is the essence of life (17:11). Bloodshed was a visual demonstration of life poured out. Sin always results in death (cf. Rom. 6:23). Clearly love lay behind this plan even though Moses did not explain why God provided atonement in Leviticus. God opened the way for sinners to have fellowship with Himself by providing for the covering of sins. God could have preserved His holiness and satisfied the demands of his justice by annihilating every sinner. However, God chose another way because He loves man.
A third major revelation in Leviticus is the nature of redemption. Redemption essentially means purchase. To redeem means to purchase for oneself. When God redeemed Israel in Egypt, He bought the nation for Himself. God then provided freedom so the Israelites could be His special treasure. Leviticus teaches three things about redemption.
1. Redemption rests on righteousness. Leviticus reveals that God did what was right to restore man to Himself. He did not simply dismiss sin as unimportant. He provided a way whereby the guilt of sin could be paid for righteously. Redemption rests on a payment to God, not pity.
2. Redemption is possible only by blood. The sacrificial shedding of blood is the giving up of life. The rites of animal sacrifice portrayed this graphically. People do not obtain redemption when they pour out their lives in service but by life poured out in death (cf. Heb. 9:22). Man's redemption cost God the life of His own Son ultimately.
3. Redemption should produce holiness. Redemption should lead to a manner of life that is separate from sin. Redemption does not excuse us from the responsibility of being holy. It gives us the opportunity to be holy. Holiness of life results from a relationship to God and fellowship (communion) with Him that redemption makes possible.
Redemption deals with the sinner's relationship to God whereas atonement deals with his relationship to sin. You have experienced redemption, but God has atoned for your sins.
I would summarize the message of Leviticus as follows on the basis of this three-fold emphasis on sin, atonement, and redemption. God has made provision for the covering of man's sin so man can have fellowship with God.
Genesis revealed that God made man in His own image to have fellowship with Himself. Man enjoyed that fellowship as long as he trusted and obeyed God. However when man ceased to trust and obey God, sin broke that fellowship. God then proceeded to demonstrate to fallen man that He is trustworthy, faithful. Those individuals who trusted and obeyed Him were able to enjoy fellowship with God again.
Exodus emphasized that God is also sovereign. He is the ultimate ruler of the universe who can and did redeem the nation of Israel. He did this so He could demonstrate to all people of all time how glorious it can be to live under the government of God.
Leviticus deals with how sinners can have fellowship with a holy God. Leviticus clarifies both the sinfulness of man and the holiness of God. The proper response of the redeemed sinner to a holy God is worship. Leviticus explains how Israel was to worship God. The Israelites worshipped God under the Old Covenant. Our worship is different because we live under the New Covenant.