well if that's allowed we should be able to have topics about politics
Politics and Religion are Beliefs. You believe in what they are saying and you back them. You disagree with what the other party/groups are saying. So you could never come to a common gound of disagreement.
You will fight, argue, make statements toward the other person or their beliefs that can violate more than 1 rule on this site.
Which is exactly why we dont allow for them. Having a opinion is 1 thing. Telling someone that their Belief is wrong cause it doesnt go along with your belief is another.