Well, you drew a distinction thats important. In the case of snake handlers and the christain scientists, they make claims of physical protection. The snake handlers fancy themselves after paul of the bible who bitten but survived without harm and the CS... well they are a special kooky, but make claims of healing and protection because illness is an illusion and prayer will heal all.
the difference is, jw’s advocate all sorts of treatment but freely admit you may well die. The stick behind the words for them is that you may die in this life but you will be resurrected for your faithfulness. Its the fine print that will always save them. They admit in every publication (blood brochure and various study publications) that you may well die for refusing blood. And thats the differance. They tell you (fine print as it may be) that you COULD die. The CS and the snake handlers make outrageous claims of protection.