I think you should show respect for others' beliefs, at least to the extent of not ridiculing them, except when those beliefs are themselves the topic of conversation. In that case, there's really no way to have the discussion without being willing to disagree.

When talking about lies people tell each other, the beliefs are the topic, whether or not you believe they are lies or truths. If you don't want to have other people weigh your beliefs in such a context, I would suggest not mentioning them during such a discussion. There are beliefs I have which I'm sure most don't share, but which I don't feel the need to defend (anymore) at every opportunity. For example, as an atheist, I wouldn't typically go to a Christian forum and announce that God doesn't exist, unless I were prepared to have my views ridiculed.

Please don't take this as meaning I think you shouldn't discuss your beliefs in this thread, but only that I think you shouldn't try to influence others not to debate you honestly by implying they're being uncivil.