Friendship is a funny thing. While all relationships go through some rough patches occasionally, a friendship is optional and should enhance your life rather than be a pain in the ass you have to worry about. At the very least a friend should let you be yourself and not who they want you to be. If not, what's it for?
When an argument with a friend leaves both parties angry, you can call it quits or take a break. But what if the friend says those slings and arrows should not get in the way of the friendship? It's a nice thought, but it doesn't always work. As the old saying goes, you can't unring a bell.
A dead friendship is sad, but not all that sad. If political beliefs or societal norms destroy the ability to actually enjoy one another's company, you weren't really friends at all.