Some denominations believe that they should trust God for healing of every illness, while, others draw the line at blood transfusions. But the Bible, over and over again, shows how God has used other people to carry out the tasks He puts before them. If I was very sick, or my children were, I would pray as I drove to the doctor’s office. I would ask the Lord to prepare the doctor so that he or she would offer a wise diagnosis and would be an extension of the Lord’s own hand.
There is often an inconsistency among those who refuse medical treatment. Yes, the Lord can heal, but could He not also put out a fire in their home if He chose to? The same people who would not take their children to the doctor will surely call the fire department if their house catches on fire.
For further study, see Luke 10 and 1 Timothy 5.