Your message will either be preaching to the choir, i.e., those who agree with you, or it will be rejected no matter how well you believe your reasoning is. I've never seen a political argument on the Internet that has changed anyone's mind. So why do it? It just raises blood pressure and can lead to really mean flaming when posts are unmoderated as on most Usenet groups. I know two guys who went at steadily for almost 10 years and to this day they occasionally snipe at each other. I mean they researched each other thoroughly. One has been convicted for drug use and assault while the other for white collar offenses such as academic theft and hanging a shingle for a discipline in a State in which he wasn't licensed
With politics and religion, I think we all have an innate desire to persuade others to our own beliefs. If your beliefs or values are weak, then it's natural to be silent on issues since it leads to more acceptance and congeniality. But if you're passionate about your beliefs or values, then it's hard to remain silent, even though it causes adversity and conflict. Jesus, Martin Luther King, and others have proven that being outspoken can change beliefs and values for the better. As humans created to care about others, we're not called to be quiet or passive. The question though is how best to speak up in order to influence others. In my experience, neither internet discourse nor face to face interaction dissuades people easily if they have strong views on the matter. But, there are two reasons to be outspoken anyway, assuming you have something righteous to share. First, some people do eventually change their mind if they hear a point of view often enough from different sources. It may take a lifetime, but repeated messaging can have an eventual influence on one's views or values. Second, while you're speaking or writing to one person, others may be listening or reading, and you never know what level of influence you may have on someone you never know or meet. One of my political/religious posts on another forum received only one response - a negative one. But it picks up another 100 reads a week. If 1 out of 100 people are influenced by that post, then my time and effort are worthwhile. It's a tough line, learning how to present your point of view effectively without digressing into an argument. I'm still working on that skill myself. But, I think we do best by speaking out on important issues. We should care enough about others to seek righteous values in the world. That requires being outspoken, but with kindness and respect, avoiding arguments, and prioritizing our concerns.
I sometimes read political forums. They get really nasty sometimes. I don't think the participants want to change any minds. I think they just like the thrust and parry of the forums. They seem to get their satisfaction out of calling each other nasty names.
Life is short. Make sure you spend as much time as possible arguing politics with strangers on the Internet.