- Anvilicious: The story is extremely unsubtle on Lewis beliefs, literally demonizing those he disagrees with by having an ancient of Hell taking responsibility for their beliefs.
- Evil Is Cool: Averting this is pretty much the whole point, as C.S Lewis was aware of this trope. Not only is Screwtape himself a stuck-up member of Hell's middle management and a cranky Jerkass with no sense of humor, but he gives tips to Wormwood on how to minimize how much The Patient can enjoy sinning.And anyway, why should the creature be happy?!
- Fanfic Fuel: The format inspired quite a few people to try and write letters from Screwtape tackling issues they care about. Most don't quite have the same charm as the original.
- Harsher in Hindsight: At one point Screwtape refers to atheism as their hot, new weapon in the 1950's. This takes on a disturbing Reality Subtext (and can be considered insightful, depending on your beliefs) given the increasing pushes for secularization in Western Society, Marxist regimes including the Khmer Rouge and the New Atheism movement.
- Values Resonance: Many of Lewis comments have aged incredibly well. His section on the Patient's mother and how being an obnoxious and demanding customer at a restaurant represents its own form of gluttony is very modern, for instance. Other examples include preaching how science and religion can coexist without going into conflict, pointing out corruption in churches, criticizing human pettiness, and examining subtle but dangerous forms of lust.
YMMV / The Screwtape Letters