‘Faith is no substitute for reason’ – I think it was Mibn2cweus who said that – and it’s exactly right. However, faith comes in various forms and whilst I see no harm in the gentle belief that after death one will be reunited with deceased loved ones in some sort of airy fairy Utopia somewhere in the sky, there is considerable harm in believing in Satan and devils and punishment, and, as is evident from this OP, that faith in a jealous, spiteful God prevails over the proven benefits of conventional medicine. Faith in an unseen, unknown supernatural being is in itself irrational, but belief that illness is wrought upon humanity by another equally malicious supernatural being, and that the absolute abandonment of the intellect to the former will remedy that is not quiet hope and trust – it’s a descent into utter madness.