I think one should be able to expect 'respect' in the sense that ad hominem attacks should be avoided, but if one has specific views on scientific or religious (or other) matters, one must expect to be asked to defend those views by explaining how one has reached those conclusions.
If a creationist says "I believe everything in the universe was created no more than ~6000 years ago", and I simply reply "OK, great. ", and in another thread I say I believe science has showed that the earth has to be billions of years old, and the same creationist replies with a simple "OK, great. ", that would be very (overly) respectful on both parties, but no one would have learned anything from it. A discussion board like this should stimulate people into thinking of why they hold a specific view. Many people have certain views simply because that's the way they've been brought up, and the views have never really been weighed up against competing ideas. Wouldn't hurt to think a little about it. It wouldn't be disrespectful to ask people to explain why they hold those views.
Unfortunately, sometimes just the act of asking the person to elaborate on the reasoning behind the views are construed as attacks. And sometimes, snide remarks and sarcasm is very tempting to use, because one feels the other person haven't thought things through. I try to avoid it, but I have probably done it anyway.
However - - as said, personal attacks ("you frickin' idiot!") only lead to animosity and hardens the other person's views, and closes them off from further thinking. So some respect should be displayed, otherwise we're just stroking our own ego and preaching to the choir, instead of possibly giving others valuable information.
But yo can't demand it, I'm afraid. The internet is a jungle. Lots of weird people out here. One has to grow a thicker skin, and also learn how these things work. Some people are trolls, only posting in order to get a rise out of people, and it takes some time to learn who is what.
Expect though, that in an internet debate, one can't just fling out assertions without being able to back them up with sources, like one can in everyday, person-to-person discussions.