"they who do the interpreting make themselves infidels by the very word of the prophet."
So What? You seem to be hung-up on whether someone meets your definition of what a muslim shoud be. They practice according to the beliefs of their particular sect.
If people want to believe in snake-handling in their church, that's their business.
I seem to be hung up on the fact that those who "misunderstand" will someday be brought to reality by their brethren and they will either be killed for abandoning Islam (according to the Book) or they will kill.
And that's the truth in a nutshell, bubba. If you think a hammer is a toothpick, you're liable to lose some teeth. 