The book of Leviticus was used as a guide for living a life pleasing to the Lord in the past. But nowadays, why do we only follow some rules and not others? (For example, we use the sexual relations guideline, but not the guideline about food and purification?)
Matt Slick, from CARM.org, takes the "traditional" approach in explaining how to apply rules from the Old Testament, including the book of Leviticus:
The Old Testament laws are categorized in three groups: the civil, the priestly, and the moral. The civil laws must be understood in the context of a theocracy. Though the Jewish nation in the Old Testament was often headed by a king, it was a theocratic system with the Scriptures as a guide to the nation. Those laws that fall under this category are not applicable today because we are not under a theocracy.
The priestly laws dealing with the Levitical and Aaronic priesthoods were representative of the future and true High Priest Jesus, who offered Himself as a sacrifice on the cross. Since Jesus fulfilled the priestly laws, they are no longer necessary to be followed and are not now applicable.
The moral laws, on the other hand, are not abolished, because the moral laws are based upon the character of God. Since God's holy character does not change, the moral laws do not change either. Therefore, the moral laws are still in effect.
In the New Testament we do not see a reestablishment of the civil or priestly laws. But we do see a reestablishment of the moral law.
Summarily, things like sexual relations fall under the moral law category and must be obeyed, but others like food and purification fall under the priestly category and do not have to be followed. I would suggest you read this article (especially the end) by J. Daniel Hays entitled, "Applying the Old Testament Laws." Hays suggests a new approach ("principlism"), which involves 5 steps.
- Identify What The Particular Law Meant To The Initial Audience
- Determine The Differences Between The Initial Audience And Believers Today
- Develop Universal Principles From The Text
- Correlate The Principle With New Testament Teaching
- Apply The Modified Universal Principle To Life Today
The authors then gives an example of how this works from Leviticus 5:2, "if anyone touches an unclean thing, whether a carcass of an unclean wild animal or a carcass of unclean livestock or a carcass of unclean swarming things, and it is hidden from him and he has become unclean, and he realizes his guilt":
Leviticus 5:2 provides an example of how the method of principlizing can be used by believers today to apply legal passages without being under the Law. The verse reads, "Or if a person touches anything ceremonially unclean—whether the carcasses of unclean wild animals or of unclean livestock or of unclean creatures that move along the ground—even though he is unaware of it, he has become unclean and is guilty." The action required to correct one’s ceremonially unclean status in this verse is described a few verses later. So verses 5–6 should also be included: "When anyone is guilty in any of these ways, he must confess in what way he has sinned and, as a penalty for the sin he has committed, he must bring to the Lord a female lamb or goat from the flock as a sin offering; and the priest shall make atonement for him for his sin." The traditional approach simply classifies these verses as a ceremonial law that no longer applies to believers today. However, using the principlizing approach, one can interpret and apply this text in the same manner as one would narrative.
What did the text mean to the initial audience? The context of Leviticus discusses how the Israelites were to live with the holy, awesome God who was dwelling in their midst. How were they to approach God? How should they deal with sin and unclean things in light of God’s presence among them? These verses are part of the literary context of 4:1–5:13 that deals with offerings necessary after unintentional sin. Leviticus 4 deals primarily with the leaders; Leviticus 5 focuses on regular people. Leviticus 5:2 informed the Israelites that if they touched any unclean thing (dead animals or unclean animals), they were defiled ceremonially. This was true even if they touched an unclean thing accidentally. Being unclean, they were unable to approach God and worship Him. To be purified (made clean), they were to confess their sin and bring the priest a lamb or a goat for a sacrifice (5:5–6). The priest would sacrifice the animal on their behalf and they would be clean again, able to approach and worship God.
What are the differences between the initial audience and believers today?
What is the universal principle in this text? The central universal principle in these verses relates to the concept that God is holy. When He dwells among His people, His holiness demands that they keep separate from sin and unclean things. If they become unclean, they must be purified by a blood sacrifice. This principle takes into account the overall theology of Leviticus and the rest of Scripture. It is expressed in a form that is universally applicable to God’s people in both the Old Testament and the New Testament eras.
How does the New Testament teaching modify or qualify this principle? According to the New Testament, God no longer dwells among believers by residing in the tabernacle or temple; He now dwells within believers by the indwelling Holy Spirit. His presence, however, still calls for holiness on their part. He demands that they not sin and that they stay separate from unclean things. However, the New Testament redefines the terms "clean" and "unclean." "Nothing outside a man can make him ‘unclean’ by going into him. Rather, it is what comes out of a man that makes him ‘unclean.’ … What comes out of a man is what makes him ‘unclean.’ For from within, out of men’s hearts, come evil thoughts, sexual immorality, theft, murder, adultery, greed, malice, deceit, lewdness, envy, slander, arrogance and folly. All these evils come from inside and make a man ‘unclean’ " (Mark 7:15, 20–23). Believers under the New Covenant are not made unclean by touching dead animals. They become unclean by impure thoughts or by sinful actions.
The New Covenant also changed the way God’s people are to deal with sin and uncleanness. Rather than bringing a lamb or goat to atone for sin, a believer’s sins are covered at the moment of salvation by the sacrifice of Christ. The death of Christ washes away sin and changes the believer’s status from unclean to clean. Confession of sin, however, is still important under the New Covenant (1 John 1:9), as it was under the Old Covenant. Christians are not under the Old Covenant, and their sins are covered by the death of Christ. Also because they have direct access to God through Jesus Christ, they no longer need human priests as mediators.
Hope this helps. Keep asking good questions such as this one.
[Answered by Pastor HM]
