The Bible shows us clearly that many physical diseases are the result of Satan's attack.
The fever of Peter's mother-in-law was an attack from Satan, and the Lord Jesus rebuked the fever (Luke 4:39). Something must have a personality before the Lord can rebuke it. We cannot rebuke a cup or a chair; we can only rebuke something that has a personality. Fever is a symptom; the Lord could not rebuke the symptom. But Satan was behind the symptom with a personality of his own. Therefore, as soon as the Lord rebuked the fever, it was gone.
In Mark 9 we see a dumb and deaf child. In man's eyes dumbness and deafness are sicknesses. But the Lord Jesus rebuked the unclean spirit, saying, "Dumb and deaf spirit, I order you, come out of him and enter into him no more" (v. 25). The dumbness and deafness of the child were outward symptoms of his demon possession; they were not ordinary illnesses. We must realize that many sicknesses are medically defined diseases. But there are many sicknesses that are actually attacks from the devil. The Bible does not say that the Lord healed the sickness but that He rebuked it. The boils on Job's body could not be healed by medicine; they were not medical illnesses; they were attacks from the devil. Unless one first deals with the devil, he has no way to deal with such sicknesses.
We admit that illnesses often occur through man's negligence of natural laws. However, it can quite often be the result of Satan's attack. In such a case one only has to ask the Lord to rebuke the sickness, and it will go away. This type of sickness often comes and goes away suddenly. It is an attack from Satan rather than an ordinary illness.
The complication lies in the fact that Satan does not want us to uncover and expose the illnesses he has inflicted. He always hides behind natural symptoms and makes us think that every sickness is the result of natural causes. If we allow him to hide behind these natural symptoms, our illness will not go away. Once we expose his work and rebuke him, the sickness will go away. One Christian had a very high fever and suffered greatly. He could not sleep and did not understand what was happening to him. Later, he was convinced that it was Satan's work. He prayed to the Lord about it, and the next day the fever went away.
When a Christian becomes sick, he should first find the cause for his illness. He should ask: Is there any proper reason for this sickness? Is this out of natural causes or is it an attack from Satan? If there is not a proper reason for the illness and you discover that it is indeed an attack from Satan, you should withstand him and reject him.
The work of Satan on man's body results not only in illness but also in death. Satan was a murderer from the beginning, in the same way that he was a liar from the beginning (John 8:44). We should withstand not only Satan's sickness but also his murdering. All thought of death is from Satan. Every notion of death as a means to escape from anything is from Satan. Satan made Job think of death. He did this not only to Job but also to every child of God. All notions of suicide, death wishes, and premature death are temptations from Satan. He tempts man to sin, and he also tempts man to die. Even thoughts of danger during one's travels are Satan's attacks. We must reject these thoughts whenever they come and not allow them to remain in us.