The medical field and the healing ministry are not opposed. In fact they belong together. God chooses how He wants to heal us; and there are cases of physical illness where God also uses the doctors as His instruments of healing. Some people come for healing and stop taking their medicines and this is not be the right thing to do, if it is not God's will.
The book of Sirach Chapter 38:1-4 says:
"Hold the physician in honor, for he is essential to you, and it was God who established his profession. From God the doctor has his wisdom, and the king provides for his sustenance. His knowledge makes the doctor distinguished, and gives him access to those in authority. God makes the earth yield healing herbs which the prudent man should not neglect; …."