Then, please, don't say anything at all.
The internet has made it all too simple to voice our opinions as loudly, fearlessly and anonymously as possible. The world is our oyster, but there's not always a pearl to be found. Thanks to the easy flow of ideas and information that the internet has allowed, some amazing things have happened; for example, scientists from across the globe can share cutting edge information and star-crossed lovers can FaceTime from different continents. Alas, some terrible things have also happened.
The plague of self-validation, for example, occurs daily on Facebook news feeds, Twitter timelines, and so on. Your so-called "friend" on a social media site voices an opinion, full to the brim with personal bias and anecdotal evidence, and presents it as an undisputed fact. We are all guilty of being this person from time to time, I'm sure, but the plot only thickens from there. Moments later, one of their so-called "friends" leaves a comment (typically a dissenting opinion) which the original "friend" in question finds extremely offensive and absolutely abhorrent. How dare someone disagree with your opinion, right? Wrong, actually.
You see, opinions are like... well, you know how the old saying goes. Hint, hint, everybody has one. The internet (more specifically, social media) has incited an epidemic of "Einsteins" on every matter known to man: politics, pop culture, art, the sciences and humanities, etc. Facebook's free flow of filterless information allows everyone to become an expert on any given topic, given they "speak" (and I use that term very loosely) loudly enough and spread their opinion far enough. Basically, we discuss the folly of man and the impending doom of America on websites meant for sharing photos of cats and mirror selfies. All humility is lost in virtual debates, as we blissfully (and ironically) ignore the Socratic saying, "true knowledge exists in knowing that you know nothing".
I'm not saying that we shouldn't share intelligent thought with one another, but I am saying that intelligent thought should be supported by fact, not feelings. And, if someone creates a post based on their feelings, it is not really any of your business anyhow (even if they did choose to broadcast it all over social media). Learn to overlook things, people. If a more conservative friend posts something you disagree with, your first response should not be a personal attack on their intelligence.... and vice versa. As humans, we are all capable of complex, individual thought and thus, no two of us will ever think exactly alike. If you feel the need to begin a debate or "correct" someone every time they say something you don't agree with, then you are not going to have very much fun living on a planet with such diverse inhabitants.
Essentially, people voicing their opinion isn't the same as them inviting you into an argument. Voicing your opinion on someone else's opinion might be cathartic for a moment, but it ends in a whole slew of misinformation and usually resentment. What is the point, anyway? If you present cold, hard facts on any issue you may be able to change someone's mind, but if they don't want your two-cents in the mix then you're probably wasting your time (and theirs). Sharing information with one another is important-- it's what makes the internet such a great thing-- but if someone shares a bit of information you don't agree with (opinion or otherwise) it is not your inherent duty to "correct" it. I learned this the hard way, considering I've created many a foe in my time because I thought I knew it all. Pro-tip: no one likes a know-it-all.
As election season heats up, I hope some of you keep this in mind. It is extremely easy to fall into the "I'm right, you're wrong" trap, especially when information can be shared and accessed so easily, but it is almost always better to take the high road in any given situation.
As a Game of Thrones fan, I must end on this note: "You know nothing, Jon Snow."