The two books I've read that have shaped my worldview the most:

Stranger in a Strange Land by Robert Heinlein - A classic SciFi novel that digs deep on relationships, politics, and religion. Like a lot of old SciFi, it's filled with blatant sexism. If you can look past that, it has a lot of great lessons.

Island by Aldous Huxley - a beautiful look at alternative societal structures, psychedelics, and the cruelty of the western world overcoming sacred places.