Which of course proves that it is religions that are against free speech
After all, what does a caucus mean? Does it mean that you have to prove you are a member of the LDS to comment in the LDS caucus? No, it means you can not disagree with what is being said. If you do, it is assumed you are not a part of the caucus.
I suggest that a scientific method caucus would be useful in that it would prevent the superstitious from polluting the discourse. It would also be suitable on the religion thread in that it meets your definition of a belief system. Faith and science are just two different episimological paradigms.
I, however, wouldn't find the caucus very useful. Those of us passionate about evolution would become the ridiculous characitures that Ben Stein accused us of being. We would exclude the people who question the science.
I think the whole idea of caucuses is probably unamerican, but definitely unFReerepublic. There are many Catholic and LDS, and Jewish forums on the net.
Many churches hold services behind closed doors.