Sorry for this vague title but I don't understand the whole passage below and didn't know what to ask specifically. Any correction to the title would be appreciated.
We all deprecate prejudice; but if all of us were not animated sacks of prejudices, and at least nine tenths of them were not the same prejudices so deeply rooted that we never think of them as prejudices but call them common sense, we could no more form a community than so many snakes.
-George Bernard Shaw (The Intelligent Woman's Guide to Socialism, Capitalism, Sovietism and Fascism)
I don't really understand what the text above means, and the problem is not the figurative expressions used but more about the structure(?) I guess.
Shouldn't it be like below?
If all of us were animated sacks of prejudices, ... we could no more form a community than so many snakes.
If we are not walking prejudices, then why does he call us people are snakes, not a community? I don't get why the negative assumption "if ~ were not" was used here.
What am I missing here and what exactly does the passage mean?