what if someone took your child and said that they must submit to some medical procedure that you either view as risky and unnecessary or extremely invasive?
Well risky or unnecessary or extremely invasive are concerns that can be brought up to the doctor if it is a valid concern, and from the doctor to the hospital, and so on, but if it is for a religious reason, no, absolutely no. Risky, unnecessary, or extremely invasive can be argued on merits beyond a schizophrenic belief that some being that created everything and everyone doesn't want you to save that childs life because of blah blah blah. You might as well just allow human sacrifice if you want to argue that parents can kill their children for religious reasons.
and then what will you do when the parents abandon the kid because he has been defiled and raped by the abhorrent medical procedures and is now viewed as being a soulless shell?
Thank you for making my point for me there, do you know how many children die from exorcisms? Just the fact that it is not zero should concern you. Then there are the people who just outright claim that a supernatural being told them to kill their children.