Having a religion forum on a non-religion site is like throwing raw meat into a pit with a bear and a tiger. Having a Christianity-only forum is no better, and probably worse. It's hard enough to get 2 Christians to agree on something, let alone excluding other religions. Inevitably discussion on religion leads to discussions on morality and why religion gets to be the end-all authority on what's right and wrong. Hot topics like abortion, gay marriage (or just homosexuality), stem cell research, etc. These topics, while there will always be a religious point of view, are not specifically religious topics, which means non-religious people will have to get in on the discussion, and then the shitstorm really ensues.