- Anvilicious: The story is very clear about Lewis' beliefs, posing that every thought and action taking you away from God is product of a devil subtly whispering in your ear. It must be noted that Lewis, a former atheist, based Screwtape's modus operandi in his own personal temptations.
- 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.
- Screwtape's complaint that cowardice is the one vice that the demons have failed to make seem attractive no longer rings true, what with the Ayn Rand's followers nowadays who claim selfishness is a virtue and self-preservation the greatest good, such that they feel no shame in cowardice and rationalize it as looking out for themselves and asserting that doing otherwise is illogical.
- Paranoia Fuel: The book suggests that every thought of a human being may be influenced and corrupted by demons so as to turn them away from God, even those thoughts which are religious in nature. Even those who think they are repenting may actually be doing no such thing.
- Values Resonance: Many of Lewis comments have aged incredibly well. For example, gluttons like the Patient's mother (an obnoxious and demanding Unsatisfiable Customer) are still sowing pain and discontent today. 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