Prompted by some twaddle I read on the web about social justice warrior tantrums over science fiction, I've gone back to reading the "classics" - Asimov's Foundation, Clarke's Childhood's End and Heinlein's The Moon Is A Harsh Mistress.
They were all horrible and I was only able to finish Heinlein's book. I could only make it through half of the other two. Reading the last quarter of Moon was like crawling through broken glass. In each case, the authors draped a science fiction robe around their own personal, political manifestos. Only Heinlein managed to work in a healthy dose of science and engineering. The other two didn't bother. Instead, Foundation and Childhood were more fantasy than anything else.
Foundation is a story of religion as a massive con game. Asimov wanted to attack religions of all sorts and so creates a story where everyone in church leadership positions are knowingly perpetrating frauds on a credulous population. It's so poorly thought out and Asimov was so dreadfully ignorant of theology that none of it is believable and a third of the way in I grew unbearably tired of what became a crude polemic.
Childhood's End has similar problems. Aliens come to Earth, orbit the planet in huge ships, don't land, but using what is effectively magic, end war, injustice, poverty, crime and all icky things. The population, freed from fear and want, goes on to achieve great things. The United Nations is the focal point of dealings with the aliens. It's a progressive's personal fantasy and it's embarrassing to read.
Clarke, like Asimov, is utterly ignorant of religion and brushes it aside with magic boxes the aliens give the people of Earth that allow them to look back at any place, any time. All religious figures are revealed to be ordinary people. Nothing to see here, Earthlings, move along. Unlike our own real world, relieved of any responsibility for their own lives, people don't turn to weed, porn and increasingly trivial outrages. (See also: microaggressions, pampered university children complaining of.) Clarke shows he knows little of human nature or faith.
Heinlein is the most readable, but only because he lays on the engineering and science good and thick. The rest of the book is his own libertarian manifesto. At first it's refreshingly different, with economic discussions included, but in the end, it turns into Reason Magazine dressed up with lasers and rockets.
I'm not as familiar with Clarke's work, but I do recall enjoying Asimov's and Heinlein's juvenile novels. I'm hoping to go back to those and find some happy nostalgia.