That sir, I believe, is the incorrect way to do it. I may believe in capitalism, and I may believe that communism is wrong and someone who supports it is misinformed. But that should not mean that I downvote all comments extolling the merits of communism. I try to keep in mind that what the commentor wrote is his/her opinion and if that comment is well-written and adds value to the discussion, it should be upvoted and encouraged.

Long story short, comments that add value, contribute positively to discussion and are insightful need to be encouraged. My stand on the topic should have no bearing.