Religions that claim universally relevant and abidingly truthful revelations have a clear interest in showing that their history is one of continuity. If you believe that your vision of God and reality in general is in some sense a gift from outside the human psyche, it won't do to allow unlimited adjustments to that vision. But all human language does adjust to historical change, even when trying to stay the same; as Cardinal Newman observed, to say the same thing as your ancestors said, you may well need to say something apparently very different. So how do you resolve the question of what is genuinely an "unfolding" of the original vision and what is an arbitrary elaboration that distorts that vision?