In the biblical context, the concept of "unclean animals" and "contamination" is primarily derived from the Mosaic Law, which outlines specific dietary and purity regulations for the Israelites. These laws are detailed in the books of Leviticus and Deuteronomy and serve as a guide for distinguishing between clean and unclean animals, as well as understanding the broader implications of ritual purity and holiness.

Unclean Animals:

The classification of animals into clean and unclean is first introduced in Leviticus 11 and Deuteronomy 14. According to these passages, clean animals are those that meet specific criteria, such as having a split hoof and chewing the cud. Examples of clean animals include cattle, sheep, and goats. In contrast, unclean animals are those that do not meet these criteria. Leviticus 11:4-8 states, "But of those that only chew the cud or have only a split hoof, you are not to eat: the camel, though it chews the cud, does not have a split hoof; it is unclean for you."

The list of unclean animals includes, but is not limited to, camels, rabbits, pigs, and various types of birds and sea creatures. Leviticus 11:10 specifies, "But anything in the seas or rivers that does not have fins and scales, of the swarming creatures in the waters and of all the living creatures in the waters, they are detestable to you."

Contamination:

The concept of contamination extends beyond dietary restrictions to encompass various aspects of daily life, including contact with dead bodies, skin diseases, and bodily discharges. Leviticus 11:24-25 explains, "These will make you unclean. Whoever touches their carcasses will be unclean until evening, and whoever picks up one of their carcasses must wash his clothes, and he will be unclean until evening."

Contamination through contact with unclean animals or other sources of impurity required specific purification rituals. These rituals often involved washing, waiting periods, and sometimes offerings to restore a person to a state of ceremonial cleanliness. Leviticus 15:31 emphasizes the importance of these practices: "You must keep the Israelites separate from things that make them unclean, so they will not die in their uncleanness for defiling My dwelling place, which is among them."

Theological Significance:

The laws concerning unclean animals and contamination are deeply rooted in the theological framework of holiness and separation. The Israelites were called to be a holy nation, set apart for God. Leviticus 20:25-26 underscores this calling: "You are therefore to distinguish between the clean animal and the unclean, and between the unclean bird and the clean. Do not become contaminated by any animal or bird or by anything that crawls on the ground; I have set these apart as unclean for you. You are to be holy to Me because I, the LORD, am holy, and I have set you apart from the nations to be My own."

These laws served as a constant reminder of the Israelites' covenant relationship with God and their need to maintain purity in all aspects of life. While the New Testament, particularly in passages such as Acts 10 and Mark 7, presents a shift in understanding these dietary laws, the Old Testament regulations remain a significant part of biblical history and theology, illustrating the broader principles of holiness, obedience, and the distinct identity of God's people.