Dostoevsky and how he depicts despair

So I've been reading 'Crime and Punishment' and 'The Brothers Karamazov' and thinking about how Dostoevsky depicts despair in line with the Christian understanding of it. I think they're so good at subtly diving into the philosophy of despair/hopelessness whilst also showing real life feelings. I was just wondering if anyone has any thoughts on some niche/specific ways he depicts and characterises despair, or what justifies the despair his characters face, etc. Additionally, if anyone has any recommendations of novels or novellas he has written that put despair at the forefront I'd love to hear them (and your thoughts on them!)