We are certainly not immune to fascism...

Some advantages we have/had over 1920s Germany:

We are older and have stronger and more well established institutions in place. The Weimar Republic was very new. Germany had a legislative body that had been in place since establishment in the 1870's. But the Kaiser still had significant real political power until the end of WWI. The Wermacht also had immense power and supported Hitler and the Nazis as RW power brokers. Germany also had the prototypical modern Military Industrial Complex.

Repubs have been eroding the institutions supporting our democracy for decades, as you have noticed. They deride it as the Deep State. The thing is, that deep state might be the only thing that can save us. How's that for irony?

I have no faith in Christianity. We do hear reports of more liberal minded Christians being on our side, but the more vocal ones are the authoritarians. With the exception of the Soviets, RW authoritarian regimes love their religions. The sheep look to the church for guidance and political leaders exploit that.

I personally know of no instance in history where a nation overcomes deep fascism from within and returns to real democracy. Fascist Spain survived until Franco died. His brand of fascism was perhaps slightly less brutal than Hitler, but not much. Generally, those countries have to be rescued from without. So we'd be looking at a Red Dawn scenario, I guess.

I still have hope, but it is fading.