If you want to be indirect, you could start with “I’m sorry, I don’t think this book meets my present needs.”

or if you want to be even less direct

“I’m sorry, I prefer to choose my own religious material”.

Or could try something like “Oh, I’m sorry, I must have mistakenly given you the impression that you should feel free to insert your religious beliefs into my life. Should we drop religion from our interactions, or should I also feel free to pass the reading material I find valuable on to you to read?”

That said, you of course are not allowed to point that out to said tacky and wrong friends. If I were you, I would say soemthing like, “My To Be Read pile could block out the sun, and I have to tackle those for a while! Speaking of books, have you read…”

I do occasionally read religiously themed books. I’ve just picked up a copy of Mere Christianity which is supposed to be the dog’s bollocks when it comes to apologist writing. If any of the religious people I know see me reading it then it might spark some lively debates. If someone lent me a book because they wanted to discuss theology then I’d be happy to join in.

As for the “What did you think?” question I think it is worth taking a moment to consider what is meant by this question. At face value it means what it literally says but very few people would ask this question in the hopes of getting an alternate view of their literature choice. What people want is for their opinion to be affirmed in the views of another. If that is all they want then it is better to tell them that it wasn’t your thing and let them off rather than argue that their viewpoint is incorrect…unless you don’t like them much.

Also The Shack is a revolting piece of puerile nonsense that no-one in their right mind should take seriously.

Another tactic would be to tell them you’ll read their book if they will sit and listen to your criticism of it when you’re done.

Or possibly better: tell them you’ll read their book if they will read your thoughts on it afterwards. If you put your thoughts down on paper it is likely to be a lot easier to be diplomatic in your criticism and to establish some form of communication rather than just start an argument. (It also means you have your response ready the next time someone lends you the same book).

Although, you should at least take a look at what the book is about. For example, a religious tract should be refused outright. A book about religion may have something interesting in it.

After the two years of dialogue that started, she gave up her fundamental belief in bible literalness. She still believes in the nebulous ‘higher power’, but accepts the 13.7 billion year old universe, evolution etc. It was fun watching her grow.

When someone offers up their faith to me, I take it as acceptance to open up a full dialogue. I just remember to start from a position of respect.

“No.” “No, but thank you.”

or take the route I’m most likely to take.
“No thank you, I prefer zombie books by modern authors.”
“No thank you, I would rather read the new D&D DM guide.”

Or if you are in a real good mood: “Have you read The Satanic Bible by Anton Lavey? I think I have a copy you can borrow. Maybe we can work out a trade?”

It’s important to remember that the person is trying to give you something they think is good. They’re trying to be nice to you. They’re trying to do you a favor. So, try to be nice back. It’s okay to tell them no, and firmly if you have to, but make sure to retain a calm and friendly tone. “Thank you, really, but I’m just not at all interested” is honest. “I’m sorry but I’m certain I’m not going to find time to read this” is firm while slightly evasive.