A series of recent events on my own Facebook experience has forced me out of blogospheric semi-retirement. I want to talk about how social media etiquette, specifically in this day and age of political and ideological posturing.
First and foremost, when you are on somebody else's wall, act as you would if you were on their front lawn or in their living room. Your Facebook page/wall is yours; their Facebook wall is theirs. Period. Do not pick fights or misbehave on another person's wall. There are, however, ways to express your views on another's wall. To do so, we need to differentiate between agreement/disagreement and respect/disrespect. These are not the same, and they should be treated as two different axes on the graph:
You'll notice by the tone of each statement or question on this graph, you're showing how you feel about the person's ideas as well as the person.
Another thing to consider is the audience on their wall. When you engage a person on their wall, all of their friends can see it. While that person may agree with you, their friends may not, so you need to be aware of a much broader audience. I recently had to unfriend and block a person from my Facebook wall (I'd like to think of him as a friend due to our shared history, but after seeing his true colors, I realized quickly that he was not the type of person I wanted to subject my other friends to, let alone myself) because he attacked one of my other friends over a rather trivial topic (not even related to politics) that I'd posted on my wall. What he didn't realize is how many people saw that, and what that did to his overall brand and reputation. I deleted his thread just to save him from himself.
Also, consider your assumptions BEFORE you comment. We all have personal filters that cloud how we see things. Do an assumption check on YOURSELF to see if you have your perceptions in the right place. This can best be done through messenger out of the public eye.
Finally, just play nice. Here are some basic rules of engagement. You don't have to compromise your own core beliefs to recognize that somebody may have different from your own.