Grammatical structure of this sentence

Question

As with most things, what happens in the US winds its way over to the UK. Including, it turns out, racist tropes. In my day job as a writer on a national newspaper, I sat next to someone who would often crack the same joke when I stood up to go for lunch. “What you getting?” he’d grin. “Fried chicken?” It infuriated me, but I could never articulate why. My colleague’s was a specific type of racism, a sort perpetuated by liberals so believing in their supposed lack of prejudice they think they can make racist jokes ironically. It wasn’t the first time someone used a racist slur against me that went over my head, like the time someone called me a golliwog and I laughed along with them, too young to understand the inference. But with fried chicken it runs deeper.

Sorry for the vague title, but I wasn't quite sure how to articulate it.

Here, I'm confused about the structure of the part marked in italics, especially the function of "so". Does "so" here mean "thus"? Is it "a sort of (racism) (which was) perpetuated by liberals, / thus believing in their lack of prejudice they think they can..." (I guess not. this doesn't make sense grammatically.)

How should I understand the structure and meaning of this sentence? How can I chunk this sentence into parts?

Thanks in advance!

Answer 1

My colleague’s was a specific type of racism, a sort perpetuated by liberals so believing in their supposed lack of prejudice they think they can make racist jokes ironically.

You can understand the sentence as follows: "My colleague's [racism] was a specific type of racism: [that is to say,] a sort [of racism] [that is] perpetuated by liberals [who believe so much] in their supposed lack of prejudice [that] they think [that] they can make racist jokes ironically."

In the phrase "liberals so believing in their supposed lack of prejudice", "so" is an adverb (one of the definitions of "so" is "to such an extent" or "to such a great extent", as in "It's so high that I can't reach it").

"So believing" can be understood as "to such a great extent believing" or "believing to such a great extent" or "believing so much" or "believing so strongly" or "who believe so strongly".