Did you ever go to the gym and you put all your wet, sweaty clothes in a bag and you forgot to take it out? What happens if you leave it for a few days in the dark corner of your trunk? Mildew grows. You might not be able to see it, but you know that something is growing because the smell is unmistakable.
In Leviticus 13, the Israelites took mildew and infections seriously because they considered the health and purity of the individual and the community to be a serious matter. An infected person was to live outside the camp for a period of time and infected articles of clothing were to be burned. Anything that was unclean or that could cause destruction or sickness was dealt with decisively.
Do we treat sin in our personal lives and in the lives of our churches with the same seriousness?