I don't think I've been objective about any book I've ever read in my life. I have no intention of starting now.

Books are written by people immersed in cultures. They depict their eras to at least some extent even if they try not to. Sometimes they depict horrifying things on purpose to argue against them. Huck Finn sincerely believes that slavery is the will of God and decides to accept eternal damnation rather than turn Jim in. That moment wouldn't make sense if Mark Twain had not written racism how he saw it.