Republicans test a new red line: Denaturalization

and the only thing that can stop them is violence at this point

There are a range of effective violent and non-violent resistance tactics. The important part is understanding that violent tactics will inevitably be necessary to complement the non-violent tactics. Violence alone doesn't work - look at the anarchists around the 1900s who assassinated a range of kings and police chiefs.

And there’s no winning against a military force like the US.

There are plenty of countries which have resisted US military invasion. They've faced atrocities and been left with horrific scars, but nonetheless this view of the mighty US military as unbeatable is repeatedly contradicted by its history. And a civil war would provide a different dynamic, so it's a bit of a mystery in my opinion. Obviously not advocating for that, and believe it or not the (whole) military is not an inevitable opponent.