I don't know if I could call myself an atheist, but I am certain that I am a humanist. I got great faith in human intelligence, resilience and capacity for compasion. Your son lives in a time when we have accomplished great things in many fields, especially the medical field. Great doctors and the right medical procedures will go much further than all the prayers of the in-laws. Spend more time involved with doctors than with the in-laws. Best for you and your family, especially your son.
I am glad there is one less minion serving the Fake-full of deceit slave