Religious people assume that clean and unclean are religious terms. When talking about unclean, they often say “ceremoniously unclean. This religious approach creeps into most English translations of the Old Testament.
The Old Testament is not a religious book. It is a spiritual book. This means that clean and unclean are spiritual terms, not religious terms.
The Hebrew word for unclean is “tame”. It means foul or dirty. The word translated as clean.is “taher”. It is much stronger than clean. It mean pure, clear or bright. It is used to describe pure gold.
We need to think about what makes things pure and other dirty. Everything God created is pure and good. Unfortunately, the spiritual powers of evil got hold of his creation (through a human mistake) and everything they touched they corrupted and make foul.
In the Old Testament, unclean (tame) means spiritually impure, ie contaminated by the spiritual power of evil. The opposite word “taher” means spiritually pure.
The laws dealing with clean and unclean describes things that Israel the children of Israel must avoid, because they are polluted by demonic powers. Their problem was that they did not have the gift of spiritual discernment, because the Holy Spirit had not yet been given. Therefore, God had to give them blanket rules listing things to avoid because they were affected by evil.
The children of Israel had come of slavery in Egypt. Evil spirits are not interested in slaves, because they are infatuated with power. They always seek to control people in positions of power, so they can leverage their influence. This meant that the Israelites came out of Egypt, relatively spirit-free. Most of the evil spirits remained behind with their Egyptian masters.
Once they came into the land, they needed to remain spirit-free, by avoiding picking up the spirits that had controlled the Canaanites. Most of these were meant to flee the land with the Canaanites, but some remained, attached to animals and things in the land.
The laws about spiritually pure- and impure-things were guidelines to the Israelites about things to avoid in their new land, because they might be controlled by evil spirits. Not every incidence of these things would be infected, but it was better to play on the safe side, because they could not tell which ones would be dangerous.
Keeping away from impure things was essential, because they did not have the ability to deal with evil spirits, so they needed to remain as spirit-free as possible. If they came under control of a spirit, they had no way to get rid of it, so it was best to avoid every situation where they could pick up an evil spirit. They must avoid all situations where they might come into contact with evil spirits that they could not control or resist.