In his book “Messages for Building Up New Believers, Volume 2”, Watchman Nee, the late Chinese church leader and Christian leader, noted that some believers become ill due to sin:
In the Old Testament, namely in Leviticus and Deuteronomy, we find God protecting the Israelites and delivering them from illnesses whenever they obeyed Him, accepted His way, obeyed His law, and abstained from sin. Here God shows us clearly that some illnesses do come from disobedience and from sin.
In the New Testament, we also find some who became ill through sin. In 1 Corinthians 5:4-5 Paul spoke of his judgment to deliver one who sinned “to Satan for the destruction of his flesh.” This shows us clearly that sickness can come from sins. If the sin is less serious, the result is sickness. If the sin is serious, the result is death. Second Corinthians 7:9-10 shows that Paul’s desire was that through illness there would be repentance, not death. When the man repented with a repentance “which is without regret,” Paul said that he should then be forgiven (2 Cor. 2:6-7). First Corinthians shows us that a person’s flesh, not his life, was delivered to Satan. To deliver one’s flesh to Satan means to cause him to become ill, not to die. This shows us clearly that the person became sick because of his sin.
Paul said that there were some in the church in Corinth who took the Lord’s bread and drank His cup without discerning the Body. As a result, they became weak and ill and a number of them died (1 Cor. 11:29-30). Clearly, disobedience to the Lord was a reason for their sickness.
There is sufficient evidence in the Word to show us that many illnesses come from sin. However, this does not mean that all illnesses come from sin. Nevertheless, the first thing you should check when you are ill is whether or not you have sinned against God. Many people can tell you that they became ill because they sinned against God.
Among the brothers and sisters that I personally know, I can name over a hundred cases to prove my point. When they check the reason for their sickness, they find that many of their illnesses come from sin. Some have disobeyed the Lord in certain areas. Others have not kept His word and have taken a wrong turn in specific instances. When they discover their sin and confess it, their sickness goes away. Many brothers and sisters have experienced this, and I myself have experienced similar things. The moment we identify the reason for our sickness, the sickness is gone. This is something that medical science cannot explain.
Illnesses may not come from sins. However, like death, very often they are the result of sins. We can discover natural causes for many illnesses, but we cannot blame these natural causes for all of our sicknesses.
Often it is clear that a man’s illness comes from sin. I remember a brother, a medical professor, who once told his students in the Shanghai Medical College in Chungking, “We found that there are natural causes for many kinds of illnesses. For example, staphylococcus, streptococcus, and pneumococcus cause a number of diseases. One kind of bacterium can produce several kinds of diseases. Different kinds of germs produce different kinds of illnesses. While doctors can discover the kind of germ that produces a certain kind of illness, we have no way of determining the reason that a germ infects one person but not another person. Ten people may enter the same room at the same time, and everyone can come into contact with the same germ. Some with good health may be infected, while others with poor health may not be infected. Normally, those who have poor health are more easily infected, and those who have good health are not as easily infected. But sometimes those with poor health are not infected, while those with good health are infected. Those who do not meet the conditions for infection are infected, while those who do meet the conditions for infection are not infected. There is no explanation for this!” He went on, saying, “We must admit that, besides natural causes, God’s sovereignty is above everything.” This is true. Often a person takes every precaution yet still becomes ill.
I still remember a classmate of mine who told me a story about his professor at the Peking University Medical College. The professor had a bad temper, but he was a very knowledgeable man. All the questions that he designed for his examinations were simple. One time he asked a very simple question: “Why does a person develop tuberculosis of the lungs?” Many students failed to give the right answer; they wrote, “Because there are tuberculosis germs.” Every such answer was marked as wrong. Eventually he told the class, “The world is full of tuberculosis germs. Does this mean that everyone in the world will be infected?” He went on to explain, “Tuberculosis germs will incubate and develop into a case of tuberculosis of the lungs only under suitable conditions. You cannot say that tuberculosis of the lungs occurs simply because there is the presence of the germs.” The students thought that as long as there were germs, there would be an illness. They forgot to point out that suitable conditions were necessary. This same thing is true when Christians become ill. There may be many natural causes for sickness, but God will allow a sickness to occur only when the right conditions are present. Without a certain environment, God will not allow any sickness to occur.