Devout
For the longest time, religion had been of little consequence to Hidan. In the infancy of his life he had followed the Snake Mother based religion of his village.
Until the raiders came. Raping, killing and pillaging, they had taken few prisoners, and those they did had been turned over to the invaders priests. Tortured and experimented on, Hidan was the lone survivor. He would be released, only to find he could not die. How many times had he attempted to end his own life? All to fail in spectacular fashion. Hidan would watch Empires rise and fall, witness all the highs and lows of humanity, even the conception of ninjutsu.
Eventually he would be found by the Cult of Jashin, and out of boredom he would join. They revered him as the second coming of their God.
Hidan was not so convinced.
The man who had lived a thousand lifetimes had long since given up hope that a God would kill him.
Alternate Character Interpretation, heck yeah! The 'Snake Mother' refers to several ancient (pre Greek/Roman) religions, mostly Mycenaean. Many ancient religions were based around a 'Mother Goddess', The Mycenaean's had one associated with snakes, probably symbolising rebirth. (sorry for the Classics lecture)