we can also discuss whether tinkerbell exists. I say no and it's a silly idea.
The discussion is still possible, though. Evidence that she exists in reality
can be presented to me, and I will listen. It would be a bad thing if I gave
the impression I thought the idea was sensible, though. It would be a bit like
lying about my ideas about reality in general, because of the implications on
related ideas. This is what we do when we respect religious viewpoints.

is able to demand respect in discussions which it doesn't deserve.
Its success in obtaining undeserved respect distorts the conclusion
of discussions, usually in the direction of "maybe God exists, who
indeed can say, ahhhh."

Meta-comment about arguments being ludicrous - that is, founded in
a collection of other ideas commonly agreed to be false, or self
contradictory in trivially obvious ways, or otherwise weak - can be 
part of truth-seeking, and not an attempt to shut down discussion,
but rather an attempt to avoid being tricked into an inconclusive
admission that anything is possible, which implies the ideas are
sort-of-true even though there's no reason at all to think that.