In a day and age in which religious claims have been demoted to mere personal, subjective opinion rather than public knowledge, any suggestion that someone’s religious views may be mistaken is perceived as a personal attack.  Why?  It’s because they cannot separate themselves from their beliefs.  To attack one is to attack the other.  Their beliefs are not something that stand outside of themselves to which they subscribe, but an autobiography about their personal tastes.  Beliefs do not have a reference “out there” to which we can appeal and evaluate, but are wholly subjective, describing the person who holds them.  To say their beliefs are wrong, then, is to say there is something wrong with them.

People believe that so long as they hold to their beliefs sincerely, they are true (for them), and no one else has any business telling them their truth is not true.  Of course they have no problem telling us that our sincerely held belief that people can be wrong in what they believe to be true is a wrong belief.  This is self-refuting.

If you find yourself in a situation where someone is objecting to your objection to their truth-claim, ask, “If I sincerely believe that sincerely believing something does not make it true, does that make it true that sincerely held beliefs can be false?”  If they say yes, then ask why they objected to your objection.  If they say no, ask them why it is that their beliefs are made true by their sincerity, but your beliefs are not.  What’s good for the goose is good for the gander.