The Future Isn't

Once you know the future, you don't know the future. You cannot know your own future, because once you know it, it inevitably will change BECAUSE you know it. So once you discover your future, you discover the ability to manipulate it, rendering your vision of the future incorrect, thus you can NEVER know the future. People who claim to have seen the future or who claim to be able to predict the future are unable to see their own personal future for this reason. There are reasons to disregard prophets, including basic disbelief, because if a prophet was to be believed, then the future could be manipulated to change the prophecy, rendering it incorrect, either because of changes made by those who knew, or because the prophecy was wrong to begin with - either way it cannot be proven.