They have no allegiance to liberal democracy: an expert on antifa explains the group
https://www.vox.com/2017/8/25/16189064/antifa-charlottesville-activism-mark-bray-interview
Sean Illing
What is antifa? Where did it come from?
Mark Bray
Anti-fascism originated in response to early European fascism, and when Mussolini's Blackshirts and Hitler's Brownshirts were ascendant in Europe, various socialist, communist, and anarchist parties and groups emerged to confront them. When I talk about anti-fascism in the book and when we talk about it today, it's really a matter of tracing the sort of historical lineage of revolutionary anti-fascist movements that came from below, from the people, and not from the state.
The sort of militant anti-fascism that antifa represents reemerged in postwar Europe in Britain, where fascists had broad rights to organize and demonstrate. You started to see these groups spring up in the 1940s and 50s and 60s and 70s. You saw similar movements in Germany in the 80s around the time the Berlin Wall falls, when a wave of neo-Nazism rolled across the country targeting immigrants. There, as elsewhere, leftist groups emerged as tools of self-defense. The whole point was to stare down these fascist groups in the street and stop them by force if necessary.
These groups in the 80s adopted the name antifa, and it eventually spread to the United States in the late 80s and into the 90s. Originally, it was known as the Anti-Racist Action Network. That kind of faded in the mid-2000s; the recent wave were seeing in the US developed out of it, but has taken on more of the name and the kind of aesthetics of the European movement.