The world would be a very bland place if no one ever argued about politics. However, emotions frequently run high around political issues, and you should therefore treat this issue with care and respect.
If you're in an environment where a stand-up, passionate political row is not desirable (an office, a dinner-party where you're being introduced to your fiancée's parents etc.), then it is probably a good idea to lay off politics altogether, or at least gauge the prevailing political climate - in these circumstances, a heartfelt consensus is bonding, dissent is likely to be damaging.
In a more knockabout environment, there is no reason not to join the fray. Just be sure that you know what you're talking about and have the facts straight before you lay into anyone. Your arguments will be much more persuasive if you keep calm, listen to other people and treat their views with respect.