Sin is a spiritual disease that has strong parallels to leprosy in the natural world. In biblical days, leprosy was a progressive, incurable, contagious disease. It was extremely dangerous to the person afflicted even if only a small area was affected.
Why would the Law pronounce a person who had become covered in the disease to be clean? Charles Spurgeon pointed out leprosy’s striking parallel to the consciousness of sin. When we think we have only a spot of sin, we are unclean, but when we realize that we are totally consumed by sin, we can be made clean! God wants us to understand that our own self-righteousness is as “filthy rags” (Isaiah 64:6). Only as we abandon our claim to being anything good before God can He come in as our great High Priest and make us clean.
Pity those who feel they only need God as a “Band-Aid” on their sin and don’t comprehend that they are totally consumed by the dreaded disease. Come to Jesus repentant, helpless, and hopeless. He will make His eternal pronouncement: You are clean!