When I was young, I would ask Bible teachers why God gave the laws found in Leviticus. Many of my teachers were very practical. My teachers told me how animals not properly cooked could cause sickness if eaten. Some informed me that if someone with a skin disease were not quarantined, this would endanger all of Israel. When it came to mold, they told me it was good to address mold like we do today, by trying to get rid of it.
Certainly God is a practical God. But there are deeper reasons for these laws. Ultimately God is making a tabernacle to usher Israel back into a new sort of Eden where God would be present with his people. Death, disease, sickness, and danger do not belong there. We understand this;, but in a world full of sinners, some times expelling danger means expelling people. For example, this leaves the problem of people with leprosy being unclean for ceremonial worship. They are cut off from Israel’s worship and community. This seems very harsh to us. Didn’t Jesus heal lepers? Why would God ostracize them and thus treat them as if they were unwelcome in this new Eden? Remember, just because the person is unclean does not mean that God cannot consider them righteous. The lepers that obeyed God’s laws for the unclean ultimately benefit from the keeping of God’s laws just like the people at the tabernacle. In many ways, the lepers were honoring God as much in their ostracism as those who obeyed God through involvement in the tabernacle. The problem arises when neighbors treat lepers as if the leper’s sin is the reason they have leprosy. God does not treat personal sin as the cause of uncleanness, but rather the unclean as those inflicted by the reality of sin in this world. Even though, ceremonially speaking, this person is unclean and thus cut off from the worship in this new Eden, their faithfulness will be the reason they will have access to the true and better heavenly Eden.