If people do not believe in permanent marriage, it is perhaps better that they should live together unmarried than that they should make vows they do not mean to keep.
 C. S. Lewis, Mere Christianity (1952). copy citation

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Author C. S. Lewis
Source Mere Christianity
Topic marriage vow
Date 1952
Language English
Reference
Note Adapted from a series of BBC radio talks made between 1942 and 1944
Weblink https://www.dacc.edu/assets/pdfs/PCM/merechristianitylewis.pdf

Context

“who would urge the high and hard duty of chastity on people who have not yet wished to be merely honest? If they have now come to their senses and want to be honest, their promise, already made, constrains them. And this, you will see, comes under the heading of justice, not that of chastity. If people do not believe in permanent marriage, it is perhaps better that they should live together unmarried than that they should make vows they do not mean to keep. It is true that by living together without marriage they will be guilty (in Christian eyes) of fornication. But one fault is not mended by adding another: unchastity is not improved by adding perjury.” source