Can you point out a reference that gave you this impression? To my knowledge this is not the case at all. All content, even the one based on religious standing, will be available to all players, just maybe not all at once in a single moment of time. If you decide to do deeds for one particular deity and gain standing with it in order to unlock new content or rewards, you may still go back and undo this progress by starting to accumulate standing with another deity or faction.