Despite its title, this essay is not about leprosy. It is about the affliction called tzara'at in Hebrew that is typically mistranslated as leprosy. Modern leprosy, more properly called Hansen's disease, is a skin condition that spreads very slowly and is clearly nothing like tzara'at.
Chapters 13 and 14 of Leviticus discuss tzara'at in detail. This affliction could affect people, garments, or buildings. In verse 14:34 God says he is responsible for causing it. It seems to be one of many scriptural afflictions we seldom or never see in our day.
Modern medicine is still trying to understand a condition named vitiligo, in which patches of the skin stop producing melanin. There are multiple causes (including the condition simply spontaneously happening) and no effective treatments. It is not contagious or unhealthy but causes obvious social problems.
From verses 13:13-14 we learn that tzara'at is identical to vitiligo except that tzara'at includes "live flesh" (in Hebrew basar chai). This phrase can refer to either inflamed flesh or open sores, but in these chapters it is specified as open sores since the tzara'at is lower than the surrounding skin. Thus tzara'at looks like open sores with a loss of pigment.
(Thus in verses 13:12-14 scripture differentiates between vitiligo and tzara'at. Someone who develops vitiligo lacks open sores and is white over his or her entire body; that person should not be labeled as having tzara'at and can be ritually pure.)
Scripture is clear that tzara'at spreads on the person who has it, but never says tzara'at is contagious. In fact, stories such as we read in Second Kings 5 (Na'aman becoming healed of tzara'at) suggest it is not contagious.
Tzara'at can also affect clothing or buildings. The text says it then looks like green or red mildew.
The Hebrew language differentiates between "signs" and "wonders". Signs show where or what something is. Wonders provide evidence that a messenger is sent from God. Tzara'at is a sign: it is a physical condition that designates someone as spiritually dead and undeserving to stay within the Israelite camp. Aharon knew this, and when he sees Miryam struck with tzara'at he asks God, "Let her please not be as one dead" (Numbers 12:12).
Someone on whom God put tzara'at, who is later healed, must do a ritual (described in verses 14:2-7) that includes an odd assortment of materials. These materials appear again in Numbers 19, where they are burned with a red heifer and the resulting ash put in water to make the "water of purification" which gets sprinkled on people who touch a corpse, or the home in which someone dies.
From this parallelism we see that someone with tzara'at is considered "spiritually dead" until they repent, are healed, and perform certain rituals. Notice in the pattern of offerings mentioned in verses 14:10-32 that unlike a normal person the spiritually dead person must do offerings of reparation for guilt and atonement for sin before the ascent offering that establishes contact and fellowship with God.
Tradition teaches that, unlike Miryam, most people were warned by tzara'at coming increasingly closer to them. There is no scriptural proof for this claim, but it follows the patterns seen in Job and the plagues upon Egypt. In the Tz'enah U'renah we read:
This is how God strikes at one with tzara'at: first the disease appears on the stones of the man's house. If this brings him to repent--good, God will forgive his sins. But if he does not repent, God sends the disease upon his clothing. If he repents--good, God will forgive his sins. If he does not, God then brings the disease upon his body. This too is sent with mercy: first it is no more than a small sore upon his head. If he repents--good; if not, He sends sh'chin, a worse sort of lesion, and if he still refuses to repent he is struck by tzara'at on his entire body.
To summarize, tzara'at was a sign, neither painful nor contagious, which spreads on someone's property and body to mark spiritual death. It was a warning to prompt repentance and restoration. It also served to quarantine from the community someone who has become a corrupting influence.
In the First Century the social stigma of having in the past been afflicted with tzara'at was severe. Even after a person had repented, was healed, and had returned to living within the community the affliction would be remembered (as with "Shimon the leper" who lived in Bethany, mentioned in Matthew 26:6).
Yeshua could cure leprosy instantly, without himself becoming ritually impure (Matthew 8:2-4). He also once bestowed this ability on his disciples (Matthew 10:8). On one occasion Yeshua cured tzara'at without touching the people afflicted (Luke 17:11-19).
Many Jewish texts describe the messiah as someone with tzara'at, because Isaiah 53 describes the messiah as afflicted by God and treated as an outcast by people. Such texts often use a play on words (for example, b. Sanhedrin 98b) because the word metzora can mean both "someone with tzara'at" and "someone white as snow".
The rules for tzara'at are placed between "bookmark" sections in Leviticus 12 and 15 that discuss becoming not whole (and thus ritually impure) due to the loss of bodily fluid. The implication is that being spiritually dead is also a lack of wholeness.
Modern psychology acknowledges that people have an innate need for religion and worship. Religious counselors have many stories of patients able to be freed from substance addiction after the patient learns to let relationship with God fill the psychological "hole" into which addiction was previously poured.
How does a person know if things are getting dangerous because his or her life has so little of God in it? These days God seldom or never afflicts people with tzara'at to designate this state. People can be spiritually dead without realizing it.
But the pattern of tzara'at remains for us. First, consider your household. Often our spouses and children are the first to see if we are behaving in ungodly ways. Ask them where you need more of God!
Then consider your demeanor. Everyone has emotional circumstances: emotions themselves are not morally good or bad. But if you normally are visibly irritable and grumpy then that is a visible sign reflecting something about your relationship with God! Perhaps you always look worried or bitter? Ask in what way you are not "whole", so God can fill and fulfill.
Finally, consider yourself. A bad habit you cannot escape is often a sign that you are, in some issue or perspective or aspect of your life, "spiritually dead". Habits or afflictions may persist until a proper perspective is learned or a certain person is forgiven.
God still wakes people up to the fact they lack wholeness and need him (or more of him) to be complete. If this is you, don't delay in seeking God! Spiritual incompleteness grows on a person, just like tzara'at did. If your family relationships visibly need more of God, don't wait until your demeanor and personal life also visibly need God.
The Kingdom of God manifests wherever Yeshua is. During his earthly ministry wholeness happened as people were healed and restored. Yeshua's followers can continuing these blessings. Establishing God's Kingdom in and around us is our inheritance and responsibility.
The priests in ancient Israel could see a spiritual death, a spiritual lack of wholeness, where tzara'at occurred, but could do nothing to cure the condition. As Yeshua's followers we have a disadvantage in lacking such a clear sign, but the greater advantage of being able to actually bring healing through Yeshua.