When you are starting a society from scratch, everything has to be dealt with. Not only must property laws and morality laws be presented, but personal protection must be addressed. Additionally, laws and practices for public health have to be put in place. After all, you are taking a diverse lot of people that have lived semi-isolated lives and now they have to live together.
This is an important part of the context of Leviticus 13 (link). The people of Israel have been living in Egypt, and the truth is we do not know for certain the conditions they have lived with. We know that the conditions of their slavery were less than pleasant, but that does not clue us in for their life situation. It is also likely that the Egyptians handled enforcement of public health in their kingdom: sometimes by exile, sometimes by execution.
Coming back to the text, what is present here are the instructions of how to deal with infectious skin disease in the community. While some people will find a great many spiritual applications and parallels in this passage, I think this is a point where we need to remember one of the fundamental keys of Biblical interpretation:
The text does not have a meaning that it has never had.
When you consider what a text might possibly mean in the Scriptures, you must consider how the original recipients of it would have taken it. Would the original Israelite audience have thought of spiritual parallels or allegories for sin?
Not likely. They would have read it as directions for how to deal with literal people with literal illnesses, facing literal separation from their families and communities unless they got better from their illness. Which, given the situation, was not that likely.
Since we are looking at the health code of an ancient society, what do we do with it? Do we establish our religious leaders as health inspectors? (Speaking as a religious leader, I’ll pass on that.)
Instead, I would propose these ideas:
1. We should take infectious diseases seriously. In all honesty, there are times that we do not. We, instead, take habit, tradition, or custom more seriously. Take your responsibility not to share your diseases with others seriously.
2. Wash your dishes. And your clothes. That’s the ending segment of the chapter: keep clean stuff, so that you don’t get sick.
3. Get a professional opinion. This is the recurring theme of the chapter: the person who has the disease does not decide if it’s bad. A third-party person makes that call. Don’t assume you are lethal or safe. Get someone who knows.
These are just basic health tips. And those are worth knowing. Keep in mind that the Christian life is lived in the midst of the practical, physical world. It is not just about spiritual elements and heavenly considerations, but about the whole of existence.