Hello Walter,
This is hardly limited to religious beliefs. It happens with political
correctness, too. Look at the recent slashdot article where Dyson
dares to question global warming:
http://news.slashdot.org/article.pl?sid=09/03/28/1558225
My own theory is that the shriller a person cries to suppress "wrong"
beliefs, the more that person fears their own beliefs might be the
ones that are wrong.
Or perhaps everyone just enjoys a public stoning now and then :-(
I think the answers is to always be willing to entertain /rational/ debate
on anything. The thought being that truth will always stand up to reason,
so unless you *want* to believe something false, you have nothing to fear
in reason