The theme is crisis.
Just about every phrasing with that word can be found. Crisis of conscience, crisis of faith, identity crisis, family crisis ...
It's a worldwide crisis and of real magnitude. The phrase "first-world problems" is overused, but most of the issues here are far beyond that. These crises affect everyone and how people react to these crises will affect everyone, too.
Also, not for nothing, this scene from The Dark Knight embodies a rather prominent theme in the book:
Coming soon, more posts on the book's tone and how I nearly had a heart attack after my first readthrough.