A board like that might end up generating a lot of locked threads... think about it. eg.
You know like wheater it's okay to leave your non-christian freinds so they don't give a bad influence on you
Lots of people on the board will have very different opinions about this subject, I personally thinking doing the above is a very bad idea. I can imagine a few people would think the opposite, and thus a thread like the above could escalate until its eventual locking
Who knows, it might work though... there is a possibility for non-volatile topics to be brought up.