Antifa are just one example of the violence and aggression that the left is promoting as a way to crush any difference of opinion. They label anyone who doesn't exhibit approved thinking as racist or sexist or just evil, and frame everything in terms of humanity's morality. We see a lot of "if you don't agree with me then you don't have a soul" kind of rhetoric these days.
So if the people on the other side are just a bunch of soulless, racist, violent, evil beings, and the fight is for the heart of humanity, then how can any means of defeating them be off the table? Conservatives (always referred to as The Far Right, no matter what they actually believe) must be silenced.
So we now have the "Resistance". This resistance isn't formally organised, but it ranges from things like refusing service to Sarah Sanders at one restaurant and then following her to another to accost her family there, to the anti-free-speech riots at campuses when Ben Shapiro speaks, to doxing ICE agents, to the attack on Rand Paul in his front yard (and recent death threats against his family), to the shooting of Steve Scalise. Conservatives just don't do these things, but on the left, they are just another way of fighting political battles.
I don't mean that conservatives can't be violent or rude, but these attacks are political acts. We somehow got through eight years of Obama without any attacks of this sort by the right against the left, and when you think of some of the rhetoric against Obama during his terms, you know it wasn't for lack of outrage.
None of this would start a civil war, though. Trump has the army and rebellion wouldn't get very far, especially since liberals don't own any guns, lol.