The dichotomy of pure and polluted is a fundamental conceptual structure in the Bible, which differs from, but sometimes intersects with, ideas of right and wrong. In the Hebrew Bible, the roots ṭhr and ṭmʾ denote purity and pollution, respectively. In the New Testament, purity and pollution are denoted by the terms katharos and akatharos (clean and unclean), miaros (defiled), and koinos (profane).

The Pentateuch includes numerous purity laws, which can be divided into three categories, although the boundaries between these are not sharp. The majority of these laws deal with ritual pollution, which results from contact with biological entities such as semen and menstrual blood and can be ritually purged. These laws appear primarily in P. In addition, both P and D include laws forbidding meats that pollute by ingestion. Another set of laws, found in P, H, and D, deal with sexual pollution, which arises from specific sexual relations that are considered problematic.

Although moral concerns are evident in some of these texts, the laws’ conceptions of pollution do not always correlate with notions of wrongdoing. Pollution operates indifferently to many considerations intrinsic to ethics, such as human agency and the effects of behavior on the well-being of others and society. In the Hebrew Bible, purity ideas for the most part coexist with ethical considerations and sometimes reflect common values and concerns. The Gospel tradition, however, suggests a tension between ritual pollution and morality that dovetails with the early church’s rejection of laws that distinguish Jews from Gentiles.

Purity Law in Modern Scholarship.

In the nineteenth and early twentieth centuries, when critical study of the Bible was largely dominated by Protestants, scholars commonly regarded the laws of ritual and dietary purity as devoid of moral and therefore religious value. While attitudes naturally began to shift as Catholics and especially Jews entered the field, the watershed moment came from outside biblical studies, with the 1966 publication of Mary Douglas’s Purity and Danger. Douglas argued that ideas of purity and pollution were not empty and meaningless but rather reflected the structures and values of the societies from which they emerged. Within biblical studies, Jacob Milgrom’s extensive research on P was largely responsible for a new wave of interest in purity law. Milgrom was particularly concerned with demonstrating the ethical value of priestly purity legislation, although his arguments on this front were not always persuasive. Jonathan Klawans’s Impurity and Sin in Ancient Judaism (2004) addressed the relationship between pollution and transgression in the Hebrew Bible as a whole, in both legal and nonlegal texts, as well as in later Judaism and the New Testament. Klawans distinguished “ritual” from “moral” impurity, the latter being a permanent condition that arises from grave sin and contaminates the sanctuary and the land but is not transmitted by physical contact. Although this distinction has some utility, the category of “moral impurity” glosses over differences among a range of pollution ideas that do not always correlate neatly with sin.

A fruitful approach advocated by Thomas Kazen (2008) views biblical concepts of pollution as outgrowths of disgust. Psychological research shows a strong connection between disgust and perceptions of contamination. Disgust elicitors tend to adhere to common domains including body products, food (especially meat), sexual behaviors, and death or corpses, as well as morally offensive acts. Within these domains, specific disgust elicitors vary among cultures, subgroups, and even individuals and can be tied to value systems (Rozin, 2008, pp. 757, 766–767). Work remains to be done to understand the contours and significance of disgust and pollution in the biblical world, but given the broad cross-cultural commonalities in this area, it is probably misguided to attribute culturally or theologically specific significance to each individual source of pollution.

Ritual Purity and Purification.

The laws of ritual purity are concentrated in P, although occasional references in other biblical texts suggest that certain basic ideas and practices were widely shared in ancient Israel throughout the centuries (e.g., Deut 23:10–11; 24:8; 1 Sam 20:26; 2 Sam 11:4). The major sources of ritual pollution in P are the carcasses of certain animals (Lev 11:24–40); genital discharges, including lochial blood (Lev 12), menstrual blood, semen, and certain irregular emissions (Lev 15); the human corpse (Num 5:2; 19; 31:19, 24); and a range of skin ailments conventionally termed “leprosy” (Heb ṣāraʿat), although the symptoms do not correspond to those of Hansen’s disease (Lev 13:1–46; Num 5:2). “Leprosy” (probably mold) can also affect an article of clothing (Lev 13:47–59) or a house (Lev 14:34–53).

Ritual pollution may be transmitted to a human or object by direct physical contact. A human corpse also transmits pollution to humans and open vessels within a tent (Num 19:14–15). Ritual pollution can and must be removed once contact with the source has ceased or the polluting condition has ended. The polluted individual must wait a fixed period of time and bathe and launder his or her clothes. (Bathing and laundering are not specified for every condition but are probably implied; Milgrom, 1991–2000, Vol. 1, p. 667.) Mild pollution, including that from semen and animal carcasses, lasts until evening. Major pollution, such as that from a human corpse, leprosy, or irregular genital discharge, lasts seven days, at the conclusion of which the individual presents a “sin” or purification offering (ḥaṭṭaʾt) and a burnt offering (ʿōlâ). Pollution from regular menstruation lasts seven days from the onset of bleeding, approximating the duration of a typical period; in other respects, menstruation is a minor pollutant (Lev 15:19–24). Pollution after childbirth occurs in two stages of decreasing severity and is twice as long after the birth of a girl as a boy (Lev 12).

The purification processes for leprosy and contact with a corpse entail additional rites. For leprosy, the blood of a bird is applied to the recovered leper and to a second, live bird, which is released. The leper shaves and brings a guilt offering (ʾāšām), the blood of which is applied to the leper and the sanctuary along with oil (Lev 14:2–18). Corpse pollution is purged by applying water mixed with the ashes of a red cow and other materials to the polluted person (Num 19).

Physical implements are purified by water or fire, depending on their material and, if polluted by a corpse, with the mixture of ashes and water used for this purpose (Lev 11:32; Num 31:22–23). Earthenware cannot be purified (Lev 11:33).

The laws of ritual purity prevent contamination of sacred space, objects, and people. Ritually polluted individuals may not contact the sanctuary and its sancta (Lev 7:20–21; 15:31; 22:3–7). The severely polluted are restricted from the camp as a whole (Lev 13:46; Num 5:2). Priests and Nazirites are forbidden from contact with the dead, although for ordinary priests (but not Nazirites or the high priest), an exception is made for immediate family members (Lev 21:1–4, 10–11 [H; cf. Ezek 44:25]; Num 6:6–7 [P]).

A common interpretation associates the sources of ritual pollution with death. Milgrom argues along these lines that the laws inculcate reverence for life (Milgrom, 1991–2000, Vol. 1, pp. 766–768, 1000–1004). This rationale accounts for the pollution of the corpse, the leper, and irregular discharge, but is less persuasive in connection with emissions from childbirth and sexual intercourse. It also fails to explain why only certain animal species pollute.

Kazen’s association of pollution with disgust makes sense of the sources of ritual pollution and also accounts for other uses of pollution language. While disgust at biological phenomena can play a role in moral thought (Rozin, 2008, pp. 762–763), it is not fundamentally an ethical matter. Failing to protect the sancta from pollution or to purify oneself in a timely fashion (Num 19:13, 20 [P]) constitute transgressions, but pollution itself, though inherently undesirable, is often unavoidable and can even be necessary in the service of a moral good, such as caring for deceased relatives. Rather than imparting moral values, the ritual purity laws guard the sacred from that which offends. In so doing, they demarcate various sancta and maintain reverence for the Deity who is the source of their holiness.

Pollution, Sin, and the Sanctuary.

Although ritual pollution is not sinful, the priestly sacrificial system links it to sin. Both those recovering from severe ritual pollution and those who have sinned inadvertently present a purification offering, and a priest applies its blood to various outer parts of the tabernacle. On the annual Day of Atonement, the high priest offers purification offerings on behalf of the entire people of Israel and applies the blood to the tabernacle, including the innermost shrine, purging it of all pollutions and sins (Lev 16:16–19 [P]).

According to Milgrom, these laws indicate that both ritual pollution and sin contaminate the sanctuary and that sacrificial blood purges it of their effects. Severe ritual pollution and individual inadvertent trespasses contaminate the outer sanctum, while the inadvertent sins of priests and the community and wanton, unrepented sins penetrate further into the tabernacle (Milgrom, 1991–2000, Vol. 1, pp. 254–261). Aspects of Milgrom’s thesis have been challenged, but his basic understanding of the purgative nature of the offering is sound. Sin and pollution are distinct, but both offend the Deity and threaten the Deity’s habitation.

Dietary Purity.

Related to the laws of ritual purity are laws that circumscribe consumption of particular meats. Division of the animal kingdom into pure and impure species appears already in the J version of the flood narrative, wherein Noah takes seven of every pure animal and two of every impure animal into the ark (Gen 7:2) and sacrifices some of each pure species after the flood (Gen 8:20). In Judges 13:4, 7, Samson’s mother is prohibited from consuming “anything unclean,” since her unborn son is consecrated as a Nazirite.

While these sources suggest that impure animals may not be sacrificed or eaten by those of special status, the Priestly and Deuteronomic law codes prohibit any Israelite from eating such animals on the grounds that all Israel is holy (Lev 11:44 [H]; 20:25–26 [H]; Deut 14:21). A taxonomy of permitted and prohibited species appears in Leviticus 11:1–47 (P and H) and Deuteronomy 14:3–21, which probably derive from a common priestly Vorlage (“prototype text”). This legislation permits quadrupeds only if they chew their cud and have cloven hooves. Marine creatures are permitted if they have both fins and scales. No such criteria are given for birds and other creatures of the air, but the texts list prohibited species, all of which are carnivorous. Deuteronomy 14:19 prohibits all winged insects, while Leviticus 11:20–23 makes an exception for those with jointed legs, such as locusts and grasshoppers.

The Priestly version stipulates that large impure quadrupeds, vermin, and pure quadrupeds that have died of natural causes transmit temporary ritual pollution to people and objects by external contact and, in the case of pure quadrupeds, by ingestion (Lev 11:24–40). By implication, P thus permits consumption of carrion, whereas D prohibits it, instructing that carrion be given to Gentiles (Deut 14:21; cf. Exod 22:30 [CC]). This distinction reflects P’s concern for ritual purity, which guards the sanctity of the tabernacle, as opposed to D’s concern for the sanctity of Israel in relation to other peoples.

Interpreters since antiquity have suggested that these laws have moral objectives. In modern times, Milgrom argued that their purpose is to restrict the taking of life (Milgrom, 1991–2000, Vol. 1, pp. 718–736). But Wright (1990) observes that taboos on particular species do not reduce overall meat consumption and that characterizing prohibited species as “detestable” (šeqeṣ; Lev) or “abhorrent” (tôʿēbâ; Deut) does not suggest reverence for their lives. More likely, the Israelites, like most other peoples, considered certain meats unsavory for various largely unspoken reasons, although the priestly systematization may have incorporated some animals that were not already taboo. Avoidance of such meats distinguished those consecrated to the Deity as well as the Deity’s own table.

Sexual Purity.

While all sexual intercourse generates temporary ritual pollution, several biblical texts indicate that specific sexual acts pollute in a more permanent fashion. Among these are four legal passages: Leviticus 18 (H; cf. Lev 20 [H]), which lists prohibited sexual relationships; Leviticus 21:7–15 (H; cf. Ezek 44:22), which restricts the women whom priests may marry; Num 5:11–31 (P), which prescribes a ritual for determining the guilt or innocence of a suspected adulteress; and Deuteronomy 24:1–4 (cf. Jer 3:1), which prohibits remarriage between a man and his divorcée if she has married another in the interim. Several nonlegal texts exhibit similar ideas (Gen 34 [J]; Jer 2:23; Ezek 23:13). Apart from Leviticus 18, these passages all attribute pollution to females, reflecting the idea that intercourse can contaminate and thereby damage a woman for her present or future husband. Leviticus 18, in contrast, attributes pollution to males and reflects H’s view that all male Israelites are holy and must remain pure (Feinstein, 2010).

Leviticus 18 prohibits incest (vv. 6–18), sex with a menstruant (v. 19), adultery (v. 20), male homosexual intercourse (v. 22), and bestiality (v. 23), as well as child sacrifice (v. 21). If the Israelites engage in these acts, they and the land will be polluted and the land will spew them out. Leviticus 21 prohibits priests from marrying prostitutes and divorcées (v. 7). The high priest must marry a virgin (vv. 13–15).

Numbers 5:11–31 states that if a man suspects his wife of adultery but has no evidence against her, he may bring her to a priest, who gives her a concoction to drink. If the woman has been polluted by adultery, she suffers a debilitating reproductive condition; if not, she conceives.

Deuteronomy 24:1–4 prohibits a man from remarrying his divorcée after she has married another. The second marriage pollutes the woman but is not prohibited, nor is the woman restricted from marrying a third man. Otherwise, the case resembles adultery: sexual relations with another man ruin a woman for her husband, even if they take place within a legal marriage.

The laws of sexual purity are sometimes characterized as “moral” in contrast to the laws of ritual and dietary purity. Yet sexual pollution is not always a direct result of wrongdoing and does not necessarily afflict the culpable party. It rather reflects Israelite notions of sexual property and propriety and distinguishes sacred people.

Purity and Ethics in the New Testament.

During the Second Temple period, the Pentateuchal purity laws developed extensively and diverse practices came to characterize Jewish sects. The historical Jesus probably did not reject the basic laws of ritual and dietary purity, though these were largely discarded by the Pauline church (Acts 15; Gal 2) even as purity remained conceptually significant for Paul (e.g., Rom 1:24).

The relationship between purity and ethics figures prominently in Mark 7:1–23 and its parallel, Matthew 15:1–20. In this narrative, the Pharisees rebuke Jesus and his disciples for defying tradition by eating with unwashed hands. Jesus responds that they have neglected the law of God to uphold that of humans and, moreover, that it is not what comes into the body that defiles but evil intentions that come from the heart, including murder, adultery, fornication, and theft (Mark 7:21–22; Matt 15:19).

The redactional history of these texts is debated, but the narrative clearly did not originally deal with the Pentateuchal laws of ritual and dietary purity but rather with a later Pharisaic tradition. Thus, Jesus did not intend to reject all dietary restrictions, as Mark has it (7:19B), but rather to downplay certain expansive practices in relation to acts and intentions understood to contaminate from within. Nonetheless, this logion and its later interpretation point to a perceived tension between concerns with contact purity and ethical considerations.




  • Douglas, Mary. Purity and Danger: An Analysis of the Concepts of Pollution and Taboo. Vol. 2 of Mary Douglas: Collected Works. London: Routledge, 2003. First published 1966 (London: Routledge & Kegan Paul). A classic anthropological work exploring the concepts of purity and contamination across cultures. A preface written for the 2002 edition includes a revision of Douglas’s original thesis on the biblical dietary laws.
  • Feinstein, Eve Levavi. “Sexual Pollution in the Hebrew Bible.” Ph.D. diss., Harvard University, 2010. An analysis of the Hebrew Bible’s use of pollution language to describe problematic sexual relationships.
  • Frymer-Kensky, Tikva. “Pollution, Purification, and Purgation in Biblical Israel.” In The Word of the Lord Shall Go Forth: Essays in Honor of David Noel Freedman in Celebration of His Sixtieth Birthday, edited by Carol L. Meyers and M. O’Connor, pp. 399–414. Winona Lake, Ind.: Eisenbrauns, 1983. A concise yet thorough examination of purity ideas in the Hebrew Bible.
  • Kazen, Thomas. Jesus and Purity Halakhah: Was Jesus Indifferent to Impurity?? Stockholm: Almqvist & Wiskell International, 2002. Argues that Jesus acted with relative indifference to aspects of ritual purity law without transgressing the bounds of Jewish views on purity in his day.
  • Kazen, Thomas. “Dirt and Disgust: Body and Morality in Biblical Purity Laws.” In Perspectives on Purity and Purification in the Hebrew Bible, edited by Baruch J. Schwartz et al., pp. 43–64. Library of Hebrew Bible/Old Testament Studies 474. New York: T&T Clark, 2008. Argues that purity laws, including those concerned with moral matters, are grounded in disgust at objectionable substances and behavior.
  • Klawans, Jonathan. Impurity and Sin in Ancient Judaism. New York: Oxford University Press, 2004. Distinguishes between ritual and moral impurity in the Hebrew Bible and explores the development of these categories in ancient Jewish writings including the Dead Sea Scrolls, Tannaitic literature, and the New Testament.
  • Milgrom, Jacob. Leviticus. 3 vols. Anchor Bible 3–3B. New York: Doubleday, 1991–2000. A monumental commentary on Leviticus that draws together Milgrom’s broad and detailed studies of Priestly law.
  • Rozin, Paul, Jonathan Haidt, and Clark R. McCauley. “Disgust.” In Handbook of Emotions, edited by Jeanette M. Haviland-Jones and Michael Lewis, pp. 637–653. New York: Guildford, 2008. An introduction to psychological research on disgust, including discussions of the link between disgust and contamination and the role of Disgust in moral thought.
  • Wright, David P. “Observations on the Ethical Foundations of the Biblical Dietary Laws: A Response to Jacob Milgrom.” In Religion and Law: Biblical-Judaic and Islamic Perspectives, edited by Edwin Firmage, Bernard G. Weiss, and John W. Welch. Winona Lake, Ind.: Eisenbrauns, 1990. Argues against Milgrom’s view (presented in the same volume and reiterated in his Leviticus commentary) that the dietary laws are motivated by reverence for animal life. Suggests that their central motivation is rather to maintain the holiness of the Israelite people by setting them apart from other nations.
  • Wright, David P. “The Spectrum of Priestly Impurity.” In Priesthood and Cult in Ancient Israel, edited by Gary A. Anderson and Saul M. Olyan, pp. 150–182. Journal for the Study of the Old Testament Supplements 125. Sheffield, U.K.: JSOT Press, 1991. Surveys the concept of purity in P, including H. Argues that sources of impurity, including those arising from moral breaches, belong to a single system and can be classified as either tolerated or prohibited.

Eve Levavi Feinstein