The Book of Mormon teaches, in many places, the danger of contentions that are of the devil: the moment a political discussion gets angry or mean-spirited, that discussion is doing more harm than good. Not all contention is bad, though, at least according to the Book of Mormon. We read in Alma 2:5 that the righteous people of Alma engaged in passionate debate about their laws, debates described as "wonderful contentions." Talking politics, it seems, can and should be a positive experience.
The old adage "never talk politics or religion in polite company" is abysmally horrible advice. First off, the entire missionary program of the Church directly contradicts the latter half of that pithy phrase: we send our young people out with the express purpose of talking religion in polite company for 18-24 months. And then we ask them to continue doing it forever after--"every member a missionary." Apparently the Lord Himself would prefer we not follow that advice.
Secondly, if we can't discuss the most important issues (politics and religion) among polite company, we avoid practicing the very skill that is required to bring people closer to Christ. In addition, we neglect our responsibility to become the type of citizenry that is able to discuss and decide and debate. We will never be that people until we start trying to become that people: through deliberation we become better able to deliberate. Finally, when we ban politics and religion from polite company, we we are overtly relegating them to impolite company.
And then we wonder why politics is sometimes so nasty.
A democracy is only functional if We the People make it so. And, if we ignore the better Picards of our nature and decline to "make it so," then we're leaving the biggest decisions of our country in the hands of folks who are more interested in turning a profit, winning an advancement, or earning a raise.
And we can't blame them: we've handed them the keys to the country and tuned out.