Use of Weapons (Culture, #3)

by Iain M. Banks

what Erens thought might just have been a trace of bitterness. “I strongly suspect the things people believe in are usually just what they instinctively feel is right; the excuses, the justifications, the things you’re supposed to argue about, come later. They’re the least important part of the belief. That’s why you can destroy them, win an argument, prove the other person wrong, and still they believe what they did in the first place.”