left·ism also Left·ism l f t z m n. 1. The ideology of the political left. 2. Belief in or support of the tenets of the political left. left ist adj., n.
I'd suggest that you...
find other students that are offended by the content and get a group together.(A group of you will have more influence than you by yourself.)Voice your complaints, with well-reasoned and researched rebuttals, to your professor the dept. chair, and whatever committee dictates textbook selection.
It should go something like this (generically):
On page x, the author says "...blah blah blah...".The evidence in the matter suggests that the author is wrong because "...".We also find the political inferences that the author makes repeatedly take away from the high points of this text.(And you should be sure to list the positive attributes of the text.)
This is one thing that I love about mathematics and e's no feminist calculus or gay cosmology or creationist graph theory.