Of course, this isn't true for your side. Your side is clearly correct, morally upstanding, and genuinely wants to help people. You're not quite so sure about those other guys, though. I mean, they say they want to help, but if they really cared, they'd support the right ways of doing things. That's how you make the world a better place, after all - the wrong policies just screw things up even more. Why do they want to screw things up even more? Could they actually be that evil?
It's fun to attack those you don't much like. Everyone gets a kick out of a good mockery of dumb ideas. There's a reason why snarky, highly opinionated pieces with zero nuance do so well, and it's not just a Facebook thing. Most newspaper opinion columnists and TV pundits are in exactly the same business, for example.
When it comes to attacking ideas, this is perfectly kosher. Ideas that can't survive an attack usually deserve to fail. But in real debate, it's not just ideas that get attacked. If you're attacking the dumb ideas, why not throw in a few attacks on the dumb people who believe them? Heck, even some of those attacks are fair too - saying that someone lacks the necessary perspective to understand why their superficially appealing ideas are wrong isn't really nice, but it can be accurate.
If you invest some time and effort into understanding the other side, though, there's one kind of personal attack that just can't survive. An attack on a group's intentions is always wrong. They can be wrong, foolish, blinded, or a hundred other faults, but there's no way that millions of people just happened to decide to burn down society for the heck of it. People tend to want the same basic things - they want safety, they want wealth, they want health, they want happiness, they want freedom, and they want fun. The exact form of those desires will vary, and people will differ in exactly whose happiness and health they want to focus on improving, but the vast majority of people want to create a society that's optimized for improving those things overall.
The First Rule of Politics: Every political movement genuinely wants to make society better.
It won't be every member of a movement, of course - malicious jerks exist everywhere. It's possible for a single malicious jerk to fool lots of people into believing something bad, but those people still honestly believe that it's designed to improve the world. It's possible to have a group that defines "society" too narrowly(this is the biggest mistake of racists, for example) and only wants to help a part of what you think of as "society", but within their definitions they really want to make it better. Again, it's quite possible for groups to be wrong in their suggested policies - if two groups disagree, at least one of them is wrong, after all - but they're honestly wrong, not simply lying to you about what they want so they can line their own pockets or something.
Corollary: If you don't understand how they can believe what they believe and still want to make the world a better place, then that's a problem with your understanding, not with their beliefs.
It seems odd to some people that you might want to understand your opponents at all. After all, if you get too close to a bad idea, it might spread. Plus, there's some people who simply fail at empathy - they're just not wired in a way that allows them to understand other people very well. But there's three reasons why I think it's still a good investment of some time, even if you're skeptical or find it difficult.
1) We're all in this together. Yeah, communists and anti-science activists may drive me up the wall, but I have to live in the same place as a bunch of them. Their views and desires matter to the government of Canada, and they should matter just as much as yours and mine. Even if it's occasionally irritating. You don't have to agree with everyone else(not least because it's physically impossible), but knowing where they're coming from and what they want should be important when setting national policy, just like everyone else's views.
2) They could be right. I wouldn't bet on it - I believe what I do because I think it's right, after all - but everybody is wrong about something at some point. I have been, and so have you. If we close ourselves off from anyone who disagrees with us, we will never have our views get challenged, and that prevents them from being corrected if we have made a mistake somewhere. If the goal is to be right, and not merely to win in a fight, this is important.
3) It helps you beat them. An opponent who is a mystery cannot be predicted or countered, they can only be fought by mindlessly throwing punches. If you know who they are, what they want, and how they think, it lets you know what their weak points are, how to target those weak points, how to convince them that your methods are the right ways of achieving their goals, and so on. Like Sun Tzu said:
“If you know the enemy and know yourself, you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory gained you will also suffer a defeat. If you know neither the enemy nor yourself, you will succumb in every battle.”Don't be a dick. People who disagree with you about politics are not generally mustache-twirling villains, they're simply misguided folks who are picking the wrong ways to try to make the world better. Understand that, treat them decently, and then kick their ass.