This is very tricky topic. That law is discriminatory in that it only allows Christian faith healers, and only a subset of Christian faith healers at that. If one faith-based pseudoscience that even states in it’s “textbook” that it is not a science:
“Christian Science eschews what is called natural science, in so far as this is built on the false hypotheses that matter is its own lawgiver, that law is founded on material conditions, and that these are final and overrule the might of divine Mind.”
-page 127 of Science and Health, which clearly separates this discipline from what is today defined as science, then other faith healers and quacks should be allowed to as well. If Christians can use an unproven and baseless pseudoscience without being charged as criminals under that law quoted in the OP, then that law is a pretty clear violation of the religious rights of Muslims, Jews, and all other religions who may have their own rules about medical treatment.
That being said, I think it is otherwise a good law. It protects dependents from caregivers who may deprive them of proper healthcare based on beliefs that the dependent may not share. For instance, if the parents of a child belong to a religion that does not allow medical procedures such as transplants, blood transfusions, and other non-natural forms of medical treatment and their child does not. If the parents refused to let the child die based on beliefs the child did not share I consider that wrong. Actually, I would consider that wrong regardless of any of their beliefs, but that is beside my point. The same goes for caregivers of the elderly and disabled. If you are in charge of making medical decisions for another human being, you should be thinking of what is best for them based on their wants and beliefs, not forcing your own beliefs on medical care on the other person. If you are unable to do that, then turn medical power of attorney over to someone who can.
Finally, I do not think that individuals should be forced to accept medical procedures that do not go along with their faith. If your religion teaches that blood transfusions are wrong, you have the right to decline that treatment. All I am saying is that when making life and death decisions for someone else you should be thinking of what they would want, not what you want for them. If this kid really was a part of a religion that does not allow proper medical care and would not have wanted that treatment even to save his life, then his parents made the right call. Of course, this begs the question on whether someone who was raised on a certain belief system really believes those things, or is just going along with the indoctrination they received about what and what not to believe.