Most 'big' books will have a theme and that's what I mean by politics.
This is not to say that theme belongs to a party-driven agenda - a book should not be in my opinion a vehicle for an organized group. Party = partie, in French, parted or departed, divided, to one side. Taking a position which is aligned to any established group degrades the author and the reader. (I hate to see authors' politics trumpeted on social media, it puts me off reading their books. No one wants their nose pushed into the swill of the trough.) Readers are intelligent people who form their own opinions and many will have experiences and opinions quite different to yours and if you only wish to speak to those who agree with you, then you should stick to social media and keep hitting the unfriend button.
'Big' books fast-forward our collective thinking, usually by crushing or condemning a commonly accepted truth or way of life. They trample on convenient, fast-food commonplace ideas.