@EatenbyBears- nice one. really hits the nail on the head, i really do think that's the crux of the problem.
@kymer&traveler- i wouldn't sever a family tie over something like belief, but it's affecting their decisions such as that one promoting unethical medical practice... i would think about it.
maybe since it is actually family, it might be worth writing a long essay explaining things (in response to those things they mentioned) thoroughly (but without provocation) to try and knock some sense into these people!