I would agree with you that in order to earn respect you must give it first. One should always approach a new person or idea with the assumption that they or it have value, and to learn as much about they or it before deciding what merits it may have for your own life.

But the problem with a religious discussion is that the very nature of most religious beliefs is anti-respect. In catholocism there is a term called animale, which is reserved for those that don't follow catholic beliefs, and means the beasts, savages, or animalistic ones. In judaism the term goyam refers to those that are not kosher, or unclean. So the parish of every faith is taught that those who do not follow the tenets of their belief system are lesser beings, not to be respected in what they say or do.

I am an athiest. I try to give everybody a fair shake no matter what they believe in. But I will admit that most athiests revere "believers" as being sub-intelligent to them. So even a culture that is apparently "free thinking" as the athiests also shut down the respect factor, because their belief system is one that states that anyone that follows a god is obviously ignorant. I don't know about you, but I have a hard time respecting ignorance. Including within myself.

So while I encourage religious debate, I don't think we can ever expect there to be a mutual respect for differing opinions within it.