What evidence is there that the Jews thought leprosy was due to sin?

Question

Some Jews seemed to think that lepersy was a punishment for sin, rather than a sin itself.

This is most probably going to sound like a stupid question either because there is a specific verse or because there really seems to be no other explanation, but where in the Bible is such indicated? That is what my teachers and priests have told me, but I can't seem to find it in the Bible.

I found this webpage, but it gives me only one verse which doesn't really answer my question:

Incurable by man, many believed God inflicted the curse of leprosy upon people for the sins they committed. In fact, those with leprosy were so despised and loathed that they were not allowed to live in any community with their own people (Numbers 5:2). Among the sixty-one defilements of ancient Jewish laws, leprosy was second only to a dead body in seriousness. A leper wasn’t allowed to come within six feet of any other human, including his own family. The disease was considered so revolting that the leper wasn’t permitted to come within 150 feet of anyone when the wind was blowing. Lepers lived in a community with other lepers until they either got better or died. This was the only way the people knew to contain the spread of the contagious forms of leprosy.

Num 5:2 says

Command the people of Israel that they put out of the camp everyone who is leprous or has a discharge and everyone who is unclean through contact with the dead.

There's a comment in the question that points out 2 Ki 15:5 and another verse Num 12:10 (whose relevance I don't understand).

Num 12:9-11 (NASB):

9 So the anger of the LORD burned against them and He departed. 10 But when the cloud had withdrawn from over the tent, behold, Miriam was leprous, as white as snow. As Aaron turned toward Miriam, behold, she was leprous. 11 Then Aaron said to Moses, "Oh, my lord, I beg you, do not account this sin to us, in which we have acted foolishly and in which we have sinned.

2 Ki 15:4-6 (NASB):

4 Only the high places were not taken away; the people still sacrificed and burned incense on the high places. 5 The LORD struck the king, so that he was a leper to the day of his death. And he lived in a separate house, while Jotham the king's son was over the household, judging the people of the land. 6 Now the rest of the acts of Azariah and all that he did, are they not written in the Book of the Chronicles of the Kings of Judah?

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Some context:

I am trying to clarify the claim I make in this Cognitive Sciences stackexchange question about mental illness:

In ancient times (or Jesus's time), uninformed people believed people who had leprosy had leprosy because they committed a grave sin or sins

Answer 1

Disease in general

Most scholars and Biblical commentaries agree that it was a common belief among the Jewish people of Jesus' day that leprosy and sickness in general was caused by sin. In the Old Testament, there are a number of passage that say doctors are of little value:

As for you, you whitewash with lies; worthless physicians are you all. (Job 13:4, ESV)

In the thirty-ninth year of his reign Asa was diseased in his feet, and his disease became severe. Yet even in his disease he did not seek the Lord, but sought help from physicians. And Asa slept with his fathers, dying in the forty-first year of his reign. (II Chronicles 16:12-13)

Instead, healing comes from prayer to God:

If there is famine in the land, if there is pestilence or blight or mildew or locust or caterpillar, if their enemies besiege them in the land at their gates, whatever plague, whatever sickness there is, whatever prayer, whatever plea is made by any man or by all your people Israel, each knowing his own affliction and his own sorrow and stretching out his hands toward this house, (2 Chronicles 6:28-29)

In those days Hezekiah became sick and was at the point of death. And Isaiah the prophet the son of Amoz came to him and said to him, “Thus says the Lord, ‘Set your house in order, for you shall die; you shall not recover.’” Then Hezekiah turned his face to the wall and prayed to the Lord... Thus says the Lord, the God of David your father: I have heard your prayer; I have seen your tears. Behold, I will heal you. (II King 20:1-2,5)

Psalms 110, brings together these idea nicely:

Some were fools through their sinful ways, and because of their iniquities suffered affliction; they loathed any kind of food, and they drew near to the gates of death. Then they cried to the Lord in their trouble, and he delivered them from their distress. He sent out his word and healed them (v17-21)

Here, "fools" are afflicted with illness because of their sinfulness and are cured when they ask God for help.

Likewise, literature of the Ancient Near East usually attribute illness either to sin or black magic.¹

In Jesus' time, we have the example of this attitude in John 9:1-2:

As [Jesus] passed by, he saw a man blind from birth. And his disciples asked him, “Rabbi, who sinned, this man or his parents, that he was born blind?”

The idea that illness and disability were caused by sin is so ingrained that Jesus' Jewish disciples assume that being born blind must be the result of sin. They don't even consider the possibility that his disability was not caused by sin. Similarly, the healing of the paralytic in Luke 5:17-30 carries a strong connotation that sin and disability were related in the Jewish mindset. In this passage, Jesus first tells the man his sins are forgiven, but the crowd is not convinced so Jesus proceeds to heal the man. Thus, Jesus is playing off their (false) belief that the man was crippled because of his sin.

The Talmud also supports the idea that this was a common understanding among the Jewish people. For example, b. shabbat 55a states "there is no death without sin and there is no suffering without iniquity". Indeed, Genesis Rabbah 63:6 supports the idea that sin can occur before birth. In this passage, Rabbi Yonhanan interprets the story of Jacob and Esah "this one ran to kill this one and this one ran to kill this one [in the womb]".

tsara'ath (leprosy)

In regard to צָרָ֫עַת/tsara'ath (usually translated leprosy, although as Daniel points out the symptoms don't really match those of leprosy) specifically, the illness usually develops after a person attempts to challenge authority, a strong indication that it is the result of a specific sin. For example, after Miriam challenged Moses (Numbers 12:10–15) and after Gehazi disobeyed Elisha (II Kings 5:20–27).

When Jesus heals "lepers" in the New Testament, he instructs them to "go and show yourself to the priest, and make an offering" (Luke 5:12-14; see also Matthew 8:3-4, Luke 17:12-14). This special command, which does not normally follow healings, is further indication that this disease has a special spiritual significance.

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¹ Encyclopedia Judaica: Leprosy

Answer 2

The Hebrew word that many English translations translate as "leprosy" is צרעת (tzara'ath). This is really a mis-translation taken from the Septuagint that has caused many people a lot of confusion. In fact, tzara'ath is a spiritual disease which has external effects similar to leprosy (blotchy skin), but which is nonetheless different from leprosy which is a physical infection that modern science understands quite well.

If we read the verses that speak about tzara'ath, it becomes obvious that it could not possibly be talking about the disease that we call "leprosy" nowadays. First of all, the progression of the disease included clothing and even houses getting tzara'ath. Furthermore, tzara'ath is not contagious whereas leprosy is. In many modern Jewish translations of the Bible, the word tzara'ath is simply transliterated rather than translated because of the inaccuracy of any understandable translation.

The Talmud (Erchim 15b-16a) discusses the cause of tzara'ath. There is some discussion over which particular sins cause one to be punished with tzara'ath, but everybody seems to agree that it is caused by some sin. As far as I know, almost all Jewish sources agree that lashon hara will result in one being punished with tzara'ath. This is learned from the fact that Miriam was struck with tzara'ath as a punishment for speaking badly about Moses's wife Tziporah.

To conclude, your sentence "In ancient times (or Jesus's time), uninformed people believed people who had leprosy had leprosy because they committed a grave sin or sins" is not really correct. The people were not uninformed; the disease that they were worried about was caused by sin. It was something different from leprosy.