Science in Christian Perspective


The Levitical Dietary Laws in the Light of Modern Science

Biology Department
Oglethorpe University Atlanta, Georgia 30319
Science Department
Babb Junior High School Forest Park, Georgia 30054


From: JASA 26 (June 1974): 61-64.

Leviticus 11 presents dietary laws, specifying which animals are "clean" (edible) and "unclean" (inedible). Nine ma/or theories to account for these dietary laws are described in this paper, giving arguments pro and con regarding each. The theories discussed are the Obedience Testing, Arbitrary Divine Command, Assertion of Divine Authority, Moral Discipline, Hygiene, Spiritual Symbolism, Pagan Worship, Religious Badge, and Eclectic theories.

The authors conclude that more evidence is needed, especially from archaeology, to come to a definite conclusion regarding the validity of any of these theories. They feel that if the original purpose of these dietary laws can be determined, then perhaps we can make modern applications of lessons from them.


One of the most obvious characteristics of orthodox conservative Jews as well as of Moslems and of the Christian groups who emphasize the Old Testament is the influence of the Levitical dietary laws on their eating habits. Yet, when one questions those who adhere to these dietary laws about the reasons for them, he receives a variety of answers.

Leviticus 11 describes "clean" animals (i.e., those which may be eaten) as follows: any animals that "part the hoof, are cloven-footed, and that chew the cud." Also, all aquatic animals that have fins and scales, and winged insects that leap (i.e., locusts, crickets, and grasshoppers) are "clean" or permitted for food.

"Unclean" animals (i.e., those that are forbidden for food) were listed as follows: camel, rock badger, hare, swine, aquatic animals lacking fins and scales, eagle, ossifrages, osprey, kite, falcon, raven, ostrich, nighthawk, sea gull, hawk, owl, cormorant, ibis, water hen, pelican, vulture, stork, heron, crawling insects, hoopoe, weasel, mouse, great lizard, gecko, land crocodile, bat, lizard, sand lizard, and chameleon.

While the Bible nowhere states specifically why the dietary laws were given, several theories have arisen to account for them. Below are brief descriptions of nine' of these theories, along with some arguments for and against their acceptance.

Obedience Testing Theory

This view asserts that the choice of animals was arbitrary, but that God's purpose was to evaluate the spirituality of the faithful. The obedience testing theory also considers the Tree of Knowledge of Good and Evil (Genesis 2) to have been arbitrarily selected, and that it was the act of disobedience that imparted the knowledge of good and evil rather than any physiological effect of the chemicals present in the fruit.

Pro: The Scriptures indicate in several places where the faith of people was tested (Job, I Kings 19, Genesis 2 and 3, etc.).

Con: The choice of animals does not appear to be arbitrary as the animals classified are consistent in certain ways as discussed below.

Arbitrary Divine Command Theory

It seems strange to some that most strict adherents of the Levitical dietary laws accept this theory, thought. They may not refer to it by this name. According to this theory, the animals were arbitrarily classified by God as clean or unclean with no specific reason whatever. We are told that to raise questions about the reasons or advantages of these laws is to evade the issue. We are to accept these laws by blind faith. The point is that God commanded, and we are to obey. "God said it. I believe it. And that settles it. Period."

Pro: If God had reasons for the laws, or if it were important for us to know of them, they would have been recorded. But such is not the case. The fact that no reasons are given is evidence that they are unnecessary for us.

Con: It seems inconsistent with a loving, just, omniscient God to be arbitrary, or to command just for the sake of commanding. The fact that the animals hold certain traits in common (shown in some of the following theories) would tend to rule out the concept that they were haphazardly or arbitrarily chosen.

Assertion of Divine Authority Theory

The purpose of these laws was to establish God's authority, and to serve as a continual reminder of His authority over and concern for His people, according to this theory. These laws are beneficial in that they tend to establish a habit of thinking frequently about God and His place in our lives.

Pro: The concept of God's establishing His authority and reminding others of it is certainly consistent with many Scripture passages, for example, the requiring of phylacteries, and redeeming each first-horn donkey with a lamb (Exodus 13:13-14); the Sabbath (Exodus 20:811); the rainbow (Genesis 9:11-17); stars (Genesis 1:14); the mark on Cain (Genesis 4:15); Miriam's leprosy (Numbers 12:10); circumcision (Genesis 17:11); and labor pangs, toil and thorns (Genesis 3:17-19). The fact that no reasons are given means none are needed. Reasons would weaken His authority.

Con: The selection of animals would seem to indicate that there was more to it than this (as indicated in certain of the following theories). It would seem arbitrary and superficial for God to assert His authority in such an unproductive fashion. Would it not be more profitable for God's kingdom and the spiritual welfare of countless people if God required His people to seek to win others to His ways? If God's purpose for these laws is simply to assert His authority, why would He not make useful laws, such as requiring the faithful to he neighborly?

Moral Discipline Theory

According to this concept, the laws were to teach moral discipline, much as it was once believed that mathematics and Latin should he taught to discipline the intellect. For similar reasons some military academies have required certain patterns of eating (i.e., special ways of holding silverware, of sitting erect while eating, etc.) in order to remind cadets constantly of their discipline.

Pro: The Bible is consistent with moral disciplinary techniques. The fact that the price of a whore and of a dog (Sodomite) were unclean tends to favor the moral interpretation of these laws. In numerous passages the Hebrews were reminded that they "came up out of the land of Egypt." (Dent. 23:4). These dietary laws would serve as similar daily reminders of their moral discipline. Nazarites were to remain unshaved and to abstain from alcohol for disciplinary reasons (Numbers 6:2-20). Paul beat his body into subjection (I Cor. 9:27). "The rod" is to be used for discipline in certain circumstances (Proverbs 10:13; 22:15; and 26:3).

Con: As with the preceding theories, the particular animals selected to be clean or unclean appear to have enough in common to warrant other explanations than this. To limit what foods may be eaten merely for reasons of moral discipline, and to allow no exceptions, could result in malnutrition, death, or forcing an immoral beaking of the laws in the event of famine, poverty, or other problems.

Hygiene Theory

The adherents of this theory point out that there is close correlation between clean animals and those that are less likely to transmit zoonoses (diseases spread from animals to man), and between unclean animals and those that are most likely to transmit worms, bacteria, and other pathogens to man,

Pro: Hogs are particularly likely to spread disease, e.g., trichinosis and Ascaris. Buzzards can transmit many of the diseases that kill the animals on which they feed. Rat meat could give those who eat it trichinosis and other diseases.
On the other hand, while cattle can give us tuberculosis, tapeworms, undulant fever, for example, they are much less likely to give us more serious diseases. Essentially the same can be said for sheep.

Any fish that "looks like a fish" is considered clean, while oysters, clams, and other sea creatures are unclean. It is noteworthy here that true fish as a rule are less likely to be carriers of zoonoses than are other aquatic animals.

Not only does the hygiene theory account for the particular selection of clean and unclean animals, but also accounts for the listing of other unhygienic things as unclean. For example, human wastes were unclean (Dent. 23:12-14), as well as cooking utensils and other solid objects which were contaminated by people with running sores (Leviticus 13:47 and 14:34-55).

Paul wrote to Timothy that he should not drink water, but should drink wine (I Timothy 5:23). Paul's reason obviously favors the hygiene theory, as water was often polluted by human wastes, carcasses and other bacteria sources.
Con: A much more sensible and practical regulation would be to specify that all animals in sanitary environments are clean, while those that are raised in unsanitary environments are unclean. Or, better still, properly cooked meat is clean, while raw or rare meat is unclean, regardless of the animal from which it comes. If this were the regulation, not only could beef, mutton, and true fishes be eaten without fear of zoonoscs, but the same would be true even of pork and other animals listed as unclean. This theory also faces the difficulty that unclean animals were let down from heaven to Peter (Acts 10:9-29 and 11:5-12), and God responded to Peter's refusal to eat with, "What God has cleansed, you must not call unclean." The fact that menstruating women and women who had just given birth were considered unclean (Leviticus 12), showed that the designation of unclean does not necessarily imply a potential source of contagion or infection. The fact that the price of a whore or of a dog (or Sodomite) was unclean shows the same. Although there are numerous poisonous plants, none is listed as unclean. And although water could he polluted by carcasses, human wastes, and other contaminants, nothing is discussed regarding clean or unclean water. Even in those days water was a main source of the spreading of disease. Paul's advice to Timothy not to drink water was of course written many centuries after the dietary laws of Leviticus, and under the circumstances of Timothy going on missionary journeys in which water could be polluted.

Some object to the Hygiene Theory on the grounds that little was then known about hygiene, while others insist that these hygiene laws prove divine inspiration. (See also Matthew 15:11).

Spiritual Symbolism Theory

It is pointed out by those who favor this theory that the clean animals have in common the fact that they all symbolize spiritual virtues, while the unclean animals symbolize spiritual vices.

Pro: It should be emphasized that the Bible is an Oriental book, and that Orientals have long been noted for symbolic and figurative speech. The Bible uses several symbols for Christ: e.g., lamb (John 1:35), lion (Revelation 5:5), root (Revelation 5:5), and grapevine (John 15:1). The Holy Spirit is symbolized by the dove (Luke 3), fire (Hebrews 12), and water (Acts 11:16). God, Satan, Israel, the church, the rebellious wicked, the Gospel, sin, and other persons and concepts are represented by still other symbols, and many of the symbols were animals. Cattle and oxen are clean animals because they represent honest hard work and obedience to duty. Donkeys are unclean as they symbolize stubbornness, spiritual stupidity, and selfishness. Snakes are unclean because they depict Satan and sin (Genesis 3:1-15). Hogs are unclean because they are greedy and look down. The horse is unclean as it symbolizes pride and human military conquest.

Con: While the Spiritual Symbolism Theory is intriguing, it has some fatal inconsistencies. The lion is unclean, yet it is used to represent Christ (Revelation 5:5) and the righteous (Proverbs 28:1). The pearl represents the church (Matthew 13:46), yet is produced by unclean clams and oysters. The symbolism in the Bible is not intended to be consistent and clearcut as this theory would assume. Thus, while doves illustrate the Holy Spirit (Luke 3:22), they also illustrate wicked Ephraim (Hosea 7: 11). The donkey is an unclean animal, yet was chosen by Christ to ride for His "triumphal entry" into Jerusalem (Matthew 21). The serpent was a symbol of Satan, but was also used for salvation (Numbers 21:9). Grapes are clean, but their juice was warned against when it is fermented (Ephesians 5:8 and I Timothy 3:3), and was forbidden to Nazarites under most circumstances (Numbers 6:3-20). The eagle is unclean, yet is used to symbolize God's power (Revelation 4:7). The lion is used to symbolize Christ (Revelation 5:5), Satan (I Peter 5:8), the righteous (Proverbs 28:1), and the rebellious wicked (Joel 1:6).

Pagan Worship Theory

It is noteworthy that the Hebrews spent centuries living among neighbors who worshipped animal-like gods. Part of the worship rites of these religions some

While the Bible nowhere states specifically why the dietary laws were given, several theories have arisen to account for them. Given here are brief descriptions of nine of these theories, with arguments for and against their acceptance.

times included the eating of these animals. Thus, the sacred animals of these pagan religions were unclean, while animals not sacred to these religions were clean.

Pro: The eagle was sacred to the Egyptians. The snake, hawk, hog, goat, and horse were sacred to other neighboring religions. Sheep, camels, true fish, and most plants were not sacred to the nations and tribes around the Hebrews, and hence were clean. The faithful were to avoid all appearance of evil (I Thessalonians 5:22). They were forbidden to eat food sacrificed to idols (Revelation 2:14, 20). It is interesting that even today Arabs consider eating with someone to be a close form of fellowship.

Con: Several plants were sacred to the pagan religions, but were not unclean (II Kings 23:4). Cattle were sacred to several groups (II Kings 17:16), yet were clean. There have long been fish gods 'tnd sea gods, yet true fish were clean. In fact, fish deities are more common than clam, oyster, or shrimp deities, yet the fish were clean while the latter were not.

Religious Badge or Mark Theory

Many peoples have done or worn certain things to distinguish themselves from others. The uniforms of certain occupations are partly for this purpose, as are some greetings, gestures, hairdos, and customs, The Jews were God's earthly chosen people (Deuteronomy 7:6), chosen to witness for Him.

Pro: The Jews were required to do several things as religious marks or badges to make them stand apart as witnesses for God: circumcise their boy babies (Genesis 17:10-27), rest on the Sabbath (Exodus 20:8-11), wear phylacteries on their foreheads (Exodus 13:16) and the like. The dietary laws were a logical extension of these religious badges. The Bible describes several other marks or badges of spiritual significance. Paul was blinded on the road to Damascus to get Paul's attention and to show God's mark of approval of Christ (Acts 9:3-9). Zechariah was struck speechless for several days as a mark of God's relationship to Christ's birth (Luke 1:1823). Moses' sister, Miriam, was marked with a whitish skin disease to show God's disapproval of her objecting to Moses' dark skinned African wife (Numbers 12:1-15). God put a mark on Cain's forehead as a warning that no one was to seek revenge against him (Genesis 4:1315). The Nazarites wore long hair and beards and ate a strict diet (Numbers 6:1-21).

Con: The selection of clean and unclean animals does not appear to he haphazard, but to fit certain patterns (as discussed in some of the foregoing theories). To prohibit certain wholesome foods merely as religious badges could result in malnutrition or death during famines. It could severely handicap the poor or physically disabled. It could result in financial exploitation and monopolies of the few clean species. It could result in upsetting the balance of nature due to extermination of some species and the ignoring of others. A more practical badge would appear to be some kind of ritual associated with food preparation or eating.

Eclectic Theory

Some Bible students prefer to combine parts of two or more of the above theories to account for the reasons behind the dietary laws. Actually, there are many variations of the eclectic theory. They obviously differ on which of the above explanations are regarded as valid, and to what extent the accepted explanations are considered to account for each animal.

Pro: The fact that the Bible does not indicate any one reason might be due to the fact that several explanations are necessary. The fact that several of the preceding theories appear to be partially valid, yet no one of them is capable of accounting for each animal indicates that some eclectic explanation is necessarily the correct one.

Con: It is difficult to evaluate the eclectic theory as its variations are so numerous. Yet, the con arguments for each of the preceding theories are sufficient to show that none is valid as understood at present. If all the links in a chain are weak, simply adding more links will not make it stronger. Adding more straw to a straw house does not make it more fireproof. Likewise, simply adding useless theories together does not make a valid explanation.


In the light of the above the authors conclude that present evidence is not sufficient to warrant total acceptance of any one of the nine theories. More evidence is needed, especially from possible future archaeological discoveries. In the meantime, it would appear that, in the light of the different kinds of dietary and other "hygiene" laws given, that some eclectic interpretation is probably correct.

It should be noted that many Christians feel that it is no longer necessary to obey the Levitical dietary laws as the Old Testament Law was our "schoolmaster" to bring us to Christ (Calatians 3:24-25). Their interest in them is primarily historical. Yet if we are able to determine the original purpose of the laws, perhaps we can make modern applications of lessons from them. For this reason it is recommended that further study be made on this subject.


1A tenth important theory was inadvertently omitted: the Social Mores Theory. It argues that all societies have certain customs and taboos, and that the dietary laws are no more than this.

American Public Health Association,  The Control of Communicable Diseases in Man. U.S. Public Health Service, 1950.
Cable, Raymond M. An Illustrated Laboratory Manual of Parasitalogy. Minneapolis: Burgess Publishing Ca., 1958.
Chandler, Ass C. Introduction to Parasitology, 9th Ed., New York: John Wiley & Sons, lay., 1949.
Lapage, Geoffrey. Animals Parasitic in Man. Glasgow: Robert MacLehase and Ca., Ltd., 1957.
Rosehury, Thendar. Life on Man, New York: The Viking Press, 1969.
Yearbook of Agriculture, The Animal Diseases. Washington: The United States Department of Agriculture, 1956.
Yearbook of Agriculture, The Food. Washington: The United States Department of Agriculture, 1959.