When discussing politics, there is an almost ubiquitous tendency for people to characterise those with viewpoints which differ from their own as ignorant, stupid, or even just downright evil. This phenomenon seems to be particularly prevalent on Facebook and other social media platforms.
It is, of course, far easier to characterise those whose political viewpoints with which you disagree as ignorant, stupid and/or evil than it is to acknowledge that those people may have a point. That their ideas may have some merit to them. That their objections and criticisms of your views, even if not entirely accurate or fair, may carry some element of truth. That your views are not as infallible as you would like to think they are and those of your political adversaries may not be as flawed as you would like to think they are.
We are all prone to bias and self-serving after-the-fact rationalisation. Remain aware of this and recognise that virtually all political views have some merit to them, but none are perfect, all have their own flaws and weaknesses. Remember that you are not your beliefs and you are free to change your beliefs in the face of new information, despite what your ego and your pride tell you.
Above all, remember that just because someone disagrees with you politically does not mean that person is necessarily ignorant, or stupid, or evil. Most people are reasonably intelligent and, most of the time, well meaning. They may just see the World in a slightly different way, which is no more or less valid than how you see the World. Or they may just have different values or priorities than you do. Ultimately, most political issues boil down to a moral judgement, and we have no way of making moral judgements objectively.
This means that no-one can ever be ‘right’ or ‘wrong’ on political matters, unless one is acting on or judging a situation based on incorrect or false information. So, by all means, discuss, debate, argue, and attempt to persuade others of the superiority of your positions. Present the facts and arguments which led you to your conclusions and dissect those of others’ to attempt to arrive at a more complete and sophisticated understanding of things.
But don’t call someone ‘an idiot’ or ‘scum’ just because they happen to disagree with you. It’s a disrespectful, intellectually lazy, ad hominem and does nothing to further your arguments or strengthen your position. If someone's ‘facts’ are wrong, or arguments are shoddy, attack the incorrect facts and the shoddy arguments, not the person making them, who in all likelihood genuinely believes them, is neither an idiot nor Satan incarnate, and is acting in good faith, just like you.