I understand (or I think I understand) how Joanne feels about discussing politics and religion. I tend to be very passionate about certain topics and I'm very stubborn, so it's usually better for me to simply keep my mouth shut. I have seen certain topics discussed and even though I really wanted to say something, I didn't.
Now, at home is a different thing. If I'm with my family, people who know me well, I'm pretty willing to give my opinion, say what I have to say. And sometimes it does get heated. I always try to be tactful, phrase things very carefully.
I noticed on one thread that Denise mentioned she'd been drinking so that probably had something to do with her attitude/state of mind.