Rabbi Steinsaltz was asked: What should be done when parents rely on religion instead of medicine to heal sick children?
"One of our sages spoke on this topic some 3,000 years ago.
He said: We humans plow our fields, plant trees and bake bread - without relying on the "natural" order of existence.
In this same way, we have a right - and sometimes also a duty - to find the best ways to treat the body and to heal it.
Jews consider life one of the supreme values and believe that one has to use every available means to save a life.
Of course, in no era do we know everything; there may be changes in medicine as well as in agriculture.
But we have always to do, and utilize, the means and knowledge that are available to us.
Not to do so is negligence, and sometimes even an unhealthy reliance on superstition."
From the website "On Faith".