Why do so many here use questions on politics and religion as a stick to beat each other with?

That's the goal of both. Politics (at least in America) will always be garbage as long as it's on a two party system. The problem is people don't know how to accept people have different views, and instead decide it's their job to prove the other right. Sometimes they are so extremist they will be for whatever their party does or says no questions asked.

As for religion, I believe that's because in most religious books it discusses the need to help convert those on a misguided path or whatever. Books like all art are based on interpretation. Most people interpret things differently which causes disagreements. *sigh*

This is partially why I'm moderate and not religious.