I was once taught this way. Faith healing. It does work. However, Jesus also said "you shall know the truth and the truth shall set you free". Truth - bacteria and virus cause a lot of disease, truth, anti-biotics kill the bacteria. So, since it is a truth, you can use medicine. A doctor can set a broken bone also. These same people will use an insecticide to kill pests, but not an anti-biotic to kill a bacteria. That being said, a lot of disease is caused by man's sin. Sexually transmitted diseases were brough in to the human race by man. Sheep carry syphilis, but they don't get it. However if you have sex with sheep, you can get it. Same with AIDS from the green monkey. Most flu is mutated by bad animal care in China between hogs and chickens in which the flu virus mutates and gets into humans. Cleanliness is also a factor. Washing your hands, keeping your wastes away from your living area and your food. Outhouses and indoor plumbing in America got rid of a lot of disease that was rampant in Europe.