The Screwtape Letters Chapter 18: Summary & Quotes

Instructor: Kerry Gray

Kerry has been a teacher and an administrator for more than twenty years. She has a Master of Education degree.

In chapter eighteen of 'The Screwtape Letters', Uncle Screwtape covers the most basic and boring of routines with his nephew, Wormwood. This lesson is an overview of sexual temptation.


As mindnumbing as it may be for him, Uncle Screwtape feels that his nephew needs some additional insight into the most commonly used of all temptations. In chapter eighteen of C.S. Lewis's The Screwtape Letters, Wormwood learns how to use the sexual pleasure created by the Enemy into a tool for the Underworld. The Underworld is a place of eternal damnation in the center of the Earth.

The Screwtape Letters
Book Cover


The Enemy created sex to be enjoyed by humans, but gave them only two choices on its use. Either they need to abstain completely or practice absolute fidelity. As the Underworld has already managed to make abstinence nearly impossible, the current work involves undermining monogamy. Hell has made great progress in attacking marriage through the mockery of a union built on 'being in love.'


While Hell believes that the verb 'to be' means 'to be in competition', the Enemy has a different philosophy. He has this nonsensical idea called love that means 'the good of one self is to be the good of another'. Screwtape mocks, 'He introduces into matter that obscene invention the organism, in which the parts are perverted from their natural destiny of competition and made to co-operate.'

Screwtape would prefer to think of sex as a means by which the strong prey on the weak, but because the Enemy associated sexual desire with affection and the production of children, families are created as another way to sneak in love.

The Joke

Here is the funny part! The Enemy defines marriage as being 'one flesh'. The apostle, Paul, expanded that to say that two people who have sex become 'one flesh'. Humans have this crazy idea that the emotional surge they call 'being in love' is more important than the spiritual bond they created during copulation.

As the bond of a Biblical marriage includes monogamy, production of children, and good intentions begins with 'being in love', humans are easily confused into thinking that if they no longer have those emotions, they do not have to stay married. In addition, a man can be persuaded into making a poor choice about who to marry if he feels any sort of sexual passion towards her.

Screwtape therefore makes these two conclusions:

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