Perhaps you remember the controversy around the “what color is this dress?” internet post. Each camp claimed their perception of the dress was the correct one and could not understand how others did not see what they saw. The same can be said for anything that one group of people insist is right, while another (just as adamantly) claims differently.
The truth of the matter with the dress is seeing it in natural light, in “real life” (so to speak). However, with regards the matter of faith and religion, the final truth of the matter will only be inarguably clear when God Himself steps in and “separates the sheep from the goats.” (In my personal opinion, the truth of those who are real Christians ought to be apparent by, as Jesus himself put it, “their fruits.” But it seems in todays’ world, Satan has managed to becloud and distort the view of people so badly, that they are truly blind in a spiritual sense.)