In my opinion the fact that the word is so vague creates the possibility of disbelief. Well that's obvious, but i mean if the "word" were to be explained in ultimate detail of the questions that might be asked, instead of striking fear into us by explaining how bad hell is, then we would be more willing to surrdender into the beliefs. Like I mean take someone who has the opportunity to steal a million dollars, and it would be easy. Without the religious or moral punishments, try to think of it as breaking the law. If he was SURe he would be caught he wouldn't do it in the 1st place. But since there's the doubt that the punishment would even occur he's more willing to do it. And also if he was sure of the reward of not doing it too. Since it's so unclear that weakens the hold it has on people.