I would say one of the tenet of the Bible and other holy books is that there are immutable. It's the words of God, and he doesn't make mistakes. (In theory at least, I've heard the Bible's translations haven't always been kind to the original text.)

That's a huge difference with the constitution, a fundamental one I'd say. And, most of the time, the people I see treating the constitution as gospel denies this very important mutability. The founding fathers were right and will always be right. The constitution must not be ammended, it is already perfect.