When we read Old Testament law, it is easy to begin with one question:
“Do we still have to keep this command today?”
Why does Leviticus prohibit certain foods while most Christians do not observe those restrictions today? Why do we still regard the prohibition of adultery as binding? Must Christians keep the Sabbath? If the Old Testament permits slavery, does that mean slavery itself was God’s ideal?
These are legitimate questions. But if we begin only with “keep it or not?”, we have already skipped a more basic question:
Why did God give this law to those people at that time?
Studying Old Testament law is a little like investigating a case. A detective does not pick up one piece of evidence and immediately announce the conclusion. The scene, the people, the background, and the sequence of events all need to be examined before the clues are put together.
This is how I have used the “Detective Bible Study Method,” O.I.L.:
Observe → Investigate → Learn / Live
O.I.L. is a practical framework I developed to help Christians read Scripture more systematically. It is not a rigid sequence in which every passage must answer every question below. Different texts require different emphases.
Think of it as a map for Bible study: do not rush to the conclusion. Observe the text, investigate its background and its development within the whole canon, and only then ask how we should learn and live today.
When reading Old Testament law, three levels are especially important:
Ancient setting → Canonical development → Present-day application
First, Do Not Rush to Divide the Law into Three Categories
A common approach begins by dividing Old Testament laws into moral, ceremonial/religious, and civil laws, and then says that moral laws remain binding while ceremonial and civil laws have been abolished.
This classification is not useless. The problem is that the Bible itself does not label each command with one of these categories. Some laws combine religious, social, and ethical dimensions.
My conclusion is therefore:
Classification can be a useful tool after interpretation, but it should not replace interpretation.
Instead of first asking, “What category does this law belong to?”, begin with: “What is this law actually doing in its original setting?”
O — Observe: Look Carefully at the Text
A detective does not arrive at the scene and immediately guess the culprit. The first task is observation. The same is true when reading law.
1. To whom is this law addressed?
To all Israel? Priests? Landowners? Men or women? People involved in a particular kind of case? Not every command in the Torah was addressed directly to every Israelite—much less directly to every Christian today.
2. What situation does it address?
Do not read only one verse. Is this a general command or case law arising from a particular dispute? Does it concern worship, family, land, criminal justice, or protection of vulnerable people? We need to know the problem before we can understand what the law is answering.
3. Does the text itself give a reason?
This matters greatly. Some laws explicitly explain their rationale—for example, Israel is repeatedly reminded that they themselves had once been resident aliens in Egypt. When the text itself tells us “why,” that evidence is normally stronger than a principle we invent afterward.
4. What happens when the law is violated?
Consequences differ: restitution, temporary uncleanness, sacrifice, being cut off from the community, or even death. The consequence itself is a clue to whether we are dealing with ritual impurity, civil responsibility, or a serious ethical offense.
5. Are there related laws elsewhere in the Torah?
Do not build an entire theology from one verse. The same issue may appear in Exodus, Leviticus, Numbers, and Deuteronomy, with different passages supplementing one another or addressing different cases.
6. If evidence is available, how did neighboring cultures address the same issue?
Ancient Israel did not live in a vacuum. Other societies also had marriage practices, slavery, land law, debt arrangements, and criminal law. Comparison with ancient Near Eastern evidence can sometimes show whether a biblical law maintains an existing institution, regulates or limits it, departs from it, transforms it, or deepens a responsibility.
Ordinary Bible reading does not require a complete course in ancient Near Eastern legal history. But when the comparison materially affects an important conclusion, further research is worthwhile. Without sufficient evidence, we should not simply claim, “Everyone in the ancient world did this.”
I — Investigate: What Is This Law Actually Doing?
After observing the text, investigation begins. One common mistake is to find an ancient law and immediately extract a preferred “timeless principle”: “This law is really about fairness.” But why fairness rather than loyalty, holiness, communal identity, inheritance, or social order? The text must supply the evidence.
1. What problem did it address in its original world?
Ask what might have happened without this law. Was it preventing exploitation, regulating debt or marriage, preserving land distribution, protecting family, ordering worship, or limiting an existing institution? This question comes before “What is the principle for today?”
2. Whom does it protect, and whom does it restrain?
Some laws clearly protect the socially vulnerable, but that cannot become our predetermined answer for every law. We should ask whether the text actually does so rather than assume it in advance.
3. Relative to existing institutions, what is it doing?
It may maintain an institution, regulate or limit it, break with certain practices, transform it, or deepen a responsibility. These are questions, not a new classification system; one law may do several things at once.
Example: Slavery
It would be inaccurate to say, “The Old Testament did not really accept slavery; it only restricted it.” Leviticus 25:44–46 does permit Israelites to acquire slaves from surrounding nations and pass them on as property to their descendants. We should not rewrite uncomfortable parts of Scripture in order to protect it.
At the same time, the Torah contains laws that restrict exploitation and abuse within slavery. Exodus 21:26–27 requires freedom for a slave whose master destroys an eye or knocks out a tooth. Deuteronomy 15 requires a released Hebrew slave not to be sent away empty-handed. Deuteronomy 23:15–16 says that an escaped slave who comes among Israel must not be handed back to the master, but may live where he chooses and must not be oppressed.
A more accurate description is therefore neither “the Torah abolished slavery” nor “God regarded slavery as the ideal institution,” but:
The Torah maintains some institutions already present in its world while also regulating and limiting them, and in some places breaking with prevailing practice.
This distinction matters: God regulating conduct within an institution does not mean that the institution itself is God’s ultimate ideal.
The Second Level: How Does the Rest of Scripture Treat It?
Even after we understand what a law was doing in the ancient world, we cannot jump immediately to “Therefore, today we should…” Christians read not only Leviticus or Deuteronomy but the whole Bible.
So ask how Scripture later treats the issue. A useful map is:
Creation → Israel’s law → Israel’s history and prophets → Jesus → New Testament church → new creation
Not every law needs to pass through all six stations. But if later biblical texts revisit the issue, we cannot pretend those texts do not exist.
4. Does later Scripture develop, modify, or reframe the matter?
The daughters of Zelophehad in Numbers 27 provide an illuminating example. The existing patrilineal inheritance arrangement had not addressed the case of a man with daughters but no sons. The daughters brought the issue to Moses; Moses brought the case before God; and God declared that they were right, supplementing the law. Numbers 36 later adds a further restriction because of the possibility of tribal land passing from one tribe to another.
At minimum, this shows that concrete Torah legislation could be supplemented and developed in new cases under divine authority.
5. How do Jesus and the New Testament treat it?
Example: Adultery
Old Testament marriage law certainly exists within ancient patriarchal structures of family, lineage, and property. But we cannot therefore conclude that the prohibition of adultery was merely an ancient cultural rule. The New Testament does not remove marital fidelity. Jesus deepens the issue to desire in Matthew 5 and, when discussing marriage in Matthew 19 and Mark 10, returns to creation.
Here we see at least continuity + deepening + theological re-grounding.
The same methodological principle applies to disputed questions such as same-sex sexual behavior. We cannot conclude that a prohibition is merely obsolete cultural legislation simply because it appears in Leviticus. We must also investigate whether the New Testament continues, re-grounds, transforms, or removes the relevant requirement. That larger question involves additional texts, original-language issues, and differences between ancient and modern understandings of sexual orientation, and deserves separate treatment.
6. Has the form changed, or the requirement itself?
Sometimes the New Testament no longer requires an earlier form while retaining theological or ethical concerns associated with it. At other times, the covenant obligation itself is no longer imposed on all Christians.
Example: Sabbath
Within the Sinai covenant, Sabbath was not an optional private spiritual practice but a serious covenant obligation. In the New Testament, however, Paul says in Colossians 2:16 that believers should not be judged regarding a festival, new moon, or Sabbath. Romans 14:5–6 also permits different practices concerning the esteem given to particular days, although that passage does not explicitly say that Paul is discussing the Sabbath in particular.
It is therefore difficult to force Sabbath into only two boxes: “still binding” or “completely abolished.” A more precise description may be: it is no longer a shared Sinai-covenant obligation for all Christians, while voluntary observance may remain.
The Law Has More Than Two Outcomes: “Keep” or “Cancel”
Across the canon, different laws may be continued, deepened, transformed, fulfilled, theologically re-grounded, no longer imposed as universal covenant obligations, or retained as voluntary practices without becoming universal requirements.
But do not turn these descriptions into another rigid classification system. Nor should “canonical development” become an assumption that Scripture must move from something “primitive” toward modern moral values. That would simply place our own morality at the destination and require the Bible to move toward us. The question is empirical: how do later biblical texts actually treat earlier laws?
L — Learn / Live: Only Now Ask How We Should Live Today
1. What does this law teach me about God?
Ask what the text shows God values, how God treats his people, what kind of community he seeks to form, and what human weakness the law exposes. But there is an important limit: do not merely ask, “What do I feel this reveals about God?” Ask instead: what evidence in the text supports the claim that this law reflects a particular aspect of God’s character, values, or purposes?
2. Is the ancient world really analogous to ours?
Sometimes yes; sometimes no. Ancient debt slavery is not the same institution as modern employment. Tribal land is not simply equivalent to private real estate. Ancient purity laws are not merely modern hygiene rules. Surface similarity is not enough to justify direct application.
3. Should we retain the original form, or live out a continuing requirement?
The answer cannot be decided in advance. Nor should we simply assume that “the form can disappear but the principle always remains.” Sometimes an entire covenant arrangement has completed its role; sometimes a concrete command is reaffirmed in the New Testament. Each case must be studied.
4. Make one final self-check
Does the “principle” or present-day application I am proposing actually arise from this passage and the wider canon, or am I projecting values I already hold back into an ancient text?
The answer will not always be comfortable. Some ancient laws really are uncomfortable. Sometimes the New Testament preserves a requirement we would prefer to dismiss as ancient culture. Conversely, some practices we were taught were “always binding” may belong primarily to the distinctive arrangements of the Sinai covenant.
The purpose of interpretation is not to prove that our instincts were right all along, but to allow Scripture to correct them.
The farther the application travels from the original text, the greater the burden of argument.
O.I.L. Reference Questions for Old Testament Law
These are not questions that must be completed as a checklist every time. They are prompts that can help us think.
O — Observe
- To whom is this law addressed?
- What is its setting, and what problem is the context addressing?
- Does the text itself give a rationale?
- What are the consequences of violation?
- Are there related laws elsewhere in the Torah?
- If evidence is available, how did other cultures or legal systems address comparable issues?
I — Investigate
- What problem did this law address in its original setting? Whom did it protect, and what did it restrain?
- Relative to existing institutions, did it maintain, regulate/limit, break with, transform, or deepen something?
- How does the rest of Scripture later treat this law, institution, or requirement?
- What is retained or changed: the original form, or the theological and ethical requirement it carried?
L — Learn / Live
- What does this teach me about God, human beings, and the kind of community God seeks to form?
- Does my present-day application arise from the text and the whole canon, or am I projecting modern values backward?
So the Next Time You Encounter a Strange Law…
Do not begin by asking, “Do we still have to keep this?” Begin by doing some detective work:
Why did God give this law to them at that time?
What was it doing in that world?
How does the rest of Scripture continue to address the issue?
Only then ask:
How should I live today?
Old Testament law is not always a simple matter of “keep” or “cancel.” Some ethical requirements are reaffirmed in the New Testament; some are deepened; some ancient institutions are regulated and later Scripture further develops their theological and ethical direction; some rituals or institutions are fulfilled or transformed in Christ; and some laws, because covenant, polity, and cultural setting have changed, no longer function in their original form as shared covenant obligations for Christians.
Whatever the outcome, Old Testament law remains Christian Scripture. The question is not only, “Must I do this?” but also: “Why does God still want me to read it?”
The Detective Bible Study Method (O.I.L.) Series
Notes and Further Reading
- O.I.L. is a practical framework I developed to help Christians study Scripture more systematically, adapting the questions to different genres.
- I later found some of William J. Webb’s tools for analyzing cultural setting, available social options, canonical development, and ethical application useful for testing and refining my earlier O.I.L. approach to law. This article does not adopt Webb’s full set of criteria as a Bible-study checklist. See William J. Webb, Slaves, Women & Homosexuals: Exploring the Hermeneutics of Cultural Analysis (Downers Grove, IL: InterVarsity Press, 2001).
- For the broader question of how Christians should understand the Sinai covenant and Old Testament commands today, see Do We Still Need to Keep the Old Testament Commands Today?