They think that being rude is a means of “speaking truth to power”. Really. Also, they tend to see manners as arbitrary constructs of our racist, sexist, homophobic, patriarchal society. Really.
In the absence of G-d, all the liberals' hang-ups about racism, sexism, homophobia, islamophobia, and "patriarchy" are just the social constructs of liberals with no objective existence. Really.
What, do they really believe that somewhere out in space is floating a gigantic marble tablet with "thou shalt not be a homophobe" carved into it in Esperanto???