For a fairly in-depth analysis, I refer you to Sadly, No!, a somewhat amusing blog whose writers and editors have done signal work in deconstructing these ten pounds of crap in a five pound book. See in particular, this post. (Side note: It's a tough audience, but I'm thrilled they've accepted me as a somewhat regular commenter in threads, and even note my modest attempts at humour).
For fairly good reason, I might add. You see, in Liberal Fascism: The Secret History of the American Left, From Mussolini to the Politics of Meaning, or Liberal Fascism (LOLcats added for readability).
In a nutshell, Goldberg takes a fairly innocuous statement, "There’s this idea that the further right you go the closer you get to Nazism and fascism, and the further left you go the closer you get to decency and all good things, or at least having the right intentions in your heart" which Jonah "proves" is wrong. This is the first of many strawmen he burns.
In other words, politics is not a spread spectrum like something you'd see in a lab, but more like a circular rainbow, in which the colours all whip around in a continuum. Go far enough out on the left, and you start to see elements of the same dogmas that you'd see on the right.
And there's the key term: dogma.
We see it in other areas of life as well. Some militant atheists, for example, are as dogmatic about their non-belief in god as some fundamentalist (Islamist, Christians, Jews, take your pick).
Similarly, some political dogmas transcend "wing" descriptions, and here, if Goldberg had stuck to this point, he might have made some philosophical point, and maybe even dug up some insight into American politics. For example, dogmatic people tend to believe their's is the one best way of running a society (sounds like Goldberg himself, but that's a digression), and it really doesn't matter if the rest of their philosophies can be labeled fascist or socialist.
What does matter is an adherence to the dogma. Alfred Meyer covers this from a geopolitical perspective in his 1978 book "Theories of Convergence" (seems to be out of print, for the good reason of losing relevance), albeit with the US and Soviet Union as examples.
What Jonah does is use this "wrap-around" to create an entirely new school of thought: that liberals are fascists.
Nevermind that he includes in this fascism people like you, me, Hillary Clinton, and Barack Obama. He also includes Mussolini, Hitler, and Stalin, AND FDR, and what dinner conversation they must have had, that quartet!
In other words, because he sees a rising of liberalism that mirrors the rise of progressivism in the 60s, Jonah has decided the best way to tamp it down is to somehow link it to fascism.
In other words, he employs the "Big Lie" of Hitler and Joseph Goebbels.
Wouldn't that make him a liberal?
Jonah, because I know you're self-involved and self-indulgent enough to read every single piece written about your specious book, let me say this right here:
You want to get in my face, in the face of millions of liberals? That's fine because it's to be expected of a dogmatist like yourself, but just know that the tar you paint with is spitting more back on you than you're able to smear on us.
Y'know, I wish I had a mommy who was a literary agent. Then my book Right Wing Nutcases And The Sale Of Cheetos would be number one in perpetuity.
THAT'S how bad a book you've written!
Would you like a Dorito, Fudgie?