You can say whatever you want, whenever you want, to whoever you want.
Go look at your Facebook feed. You can say whatever you want and there is little to no recourse for saying something wrong, offensive, or polarizing. You might get some rough comments from people polarized the opposite direction as you. You might get affirmation from people who agree with you.
But either way, you can say whatever you think to be true to a community of people who have decided they want to be your friend.
Is this really so different from two thousand years ago sitting around in the local city gates or town square and talking about the politics of the day? You could say whatever you want then too.
If you walked up to the conversation and someone didn’t want to hear what you had to say, they could walk away. But I am guessing people still sat around and agreed with their counterparts and objected against the other side.
The only difference I can see today is scale. Facebook connects us to more people than before. Today we are responsible for what we say just as much as we were 2000 years ago. And the same as 2000 years ago, the guy who thinks the earth is flat was not persuaded otherwise over the campfire or the Facebook post. Nothing any of the round earth people said ever made a difference. Why would they be persuaded today?
Should you post the next opinionated Facebook post? Should you gush your opinion into the comment section of your friend’s political post? Should you really post that? Should you really?