It's not about ideology, particularly. It's not about never swearing or never getting passionate or even never personally insulting anybody.
It's about: can you, ever, in any circumstances, meet the other person halfway? A quarter of the way? A tenth of the way?
Are you capable of grasping nuance, even a little bit?
Can you, even partially, even grudgingly, ever admit, in any circumstances, that you were wrong? About anything?
Would you, once in a great while, be willing to put aside your overwhelming need to have the last word?
Can you concede, even ungraciously, that even a loathed enemy might have a point, if you can see that sie does?
Are you aware that conversations take place over time, that they're about 90% about relationships, even of the most superficial sort?
Have you ever changed your mind? About anything? Do you think it's possible you might conceivably ever change it again? About anything?
Maybe that's not anyone else's definition of civil discourse. But those are (among) the criteria I use to determine whether or not I'm going to continue bothering to talk to someone.