Modern readers can easily assume that biblical language about clean and unclean means sanitary and unsanitary. In many passages, however, the subject is ritual status rather than dirt, germs, or personal hygiene.
The Torah established categories of ritual purity and impurity connected with such matters as bodily discharges, childbirth, certain skin conditions, corpses, and particular animals. Second Temple Jewish groups interpreted and practiced these laws in ways that sometimes differed from one another.
A person could be freshly washed yet still be ritually impure, or could undergo the required purification without the issue having begun as a matter of physical dirt. At other times ordinary washing and ritual washing naturally occurred close together.
The widespread appearance of ritual immersion pools and chalkstone vessels at Jewish sites demonstrates that purity concerns affected material life. These objects and installations are especially prominent in the late Second Temple period.
Biblical, Second Temple, and later Jewish writings distinguish many causes and degrees of ritual impurity. These sources also show disagreement among Jewish groups concerning how purity laws should be interpreted and applied.
Leviticus is central to the biblical laws of purity. Its categories concern fitness for participation in sacred life and should not be reduced to ancient theories about hygiene or disease prevention.
Jesus' encounters with people described as unclean, His discussions of handwashing, and Gospel references to purification make more sense when ritual status is distinguished from ordinary dirt. The Gospel writers and their first audiences inhabited a world in which that distinction was familiar.
Ritual purity was a genuine religious concern in first-century Jewish society and is independently attested by both texts and archaeology.
Practices were not necessarily identical among all Jews. Priests, Pharisees, Sadducees, the Qumran community, ordinary households, and other groups could differ in the strictness or interpretation of particular purity rules.
Keeping ritual purity separate from modern ideas of hygiene prevents serious misunderstandings of biblical passages concerning washing, impurity, food, vessels, disease, and religious practice.