Quoted By:
There's plenty of extra-biblical evidence for the deaths of the disciples as well, and again they remained consistent throughout life and death. This isn't like Islam where there's abrogation and hadiths and Mohammed constantly changed his stories so that now none of them agree on what counts and what doesn't. It's not like mormonism, where it's essentially proven that Joseph Smith was making it up as he went along, and then was changed drastically after his death by Brigham Young (I think?).
Yes there's plenty of different Christian denominations, but those splits happened over time and are a matter of people further and further away from the source continuing to mess it up, but they'd all agree that the original disciples were correct, and then 'we' interpreted things wrong over time due to our own faults and not because the source was wrong.