I can't agree with the sentiment that Hidan is already dead. I understand the logic, but if the very first time a killing move was performed on Hidan he was already "immortal", either through a Jashinist ritual or something else yet revealed, then he is still alive and will never die. I presume when Hidan's mother gave birth to him, it was in the usual way and he was a baby once and wasn't immortal then, similar to Tenzen from Basilisk. A couple of people mentioned Amaterasu, and that would likely be successful in permanently incapacitating Hidan. Someone also mentioned Dust Release. A couple of weeks ago in a similar thread I mentioned that Particle Style: Detachment of the Primitive World Technique would totally finish Hidan. A technique like that which disintegrates you on an atomic level, unless someone creates a jutsu that can combine molecules to form humans (like an anti-dust release), would render all Naruto-universe characters permanently incapacitated. Using Amaterasu could be countered if Hidan had a Mangekyou-wielding partner on par with Sasuke who can extinguish the black flames.
