Look this video, a discussion between some college aged American socialists and a man who actually lived under their proposed system in the USSR:
Some things I noticed in their attitude:
1 They don't want to reason or discuss anything with him. They just want to argue.
2 What happened in the USSR wasn't "True" socialism, except under Stalin. No matter that communism has failed every time it has been tried- THAT is just because they didn't do it "right" and that is because they weren't as smart as us.
3 Anyone who disagrees with them is a Nazi/fascist/ racist and will be properly disposed of by being thrown in a "labor camp" once they are in charge, if they live that long.
This is what we are up against. They are willing to kill and use force to achieve their goal. There is no reasoning with them. How do you stop them from wanting to load you into the boxcars? There is, I am afraid, only one way: you must use violence to stop them BEFORE they gain power.
Things are going to get ugly, one way or the other.