Look...I'm a Christian and believe with all my heart that Christianity is the only true and correct religion.
With that said, I try very hard not to disrespect the beliefs of pagans, hindus, buddhists, Confucians, Cao Dai and so forth. While I don't believe there is any legitmacy or reality to their religion, nonetheless I recognize that it is their sincerely held belief, something that perhaps means a great deal to them, and try to treat it with appropriate respect....such as NOT calling them "loonies" for what they believe, no matter how crazy it sounds to me. I may try to convert them to Christianity, if it seems like they might be open to that possibility, but I won't denigrate them personally for believing what they believe.
(Yeah, I make an exception for radical Islam...I'm not that utterly consistent, so sue me.)
If I encounter a mother who is convinced her children are beautiful and brilliant, when in fact they are homely and dimwitted, I am not going to say "You're a delusional looney, your kids are ugly and stupid." It may be fact, from my perspective, but it would be very cruel to say so to her in such a blunt manner.
A little bit more respect for other's deeply-held spiritual beliefs on DP would go a long way towards furthering civil discourse.