I have posted a number of comments on the possibility of imposing liability on parents when they cause an injury to a child when refusing to provide medical care because of religious beliefs. See here. I have also posted on the relationship of this issue and the debates on vaccines. See here.
Here is an update: The California state Senate just overruled a long-standing law
that permitted parents with religious and philosophical reservations to
send their children to public and private schools without their shots.
Slate has a recent article on the issue called "Faith Healing Kills Children." You can read it here.