The powers which enable evil to carry on are powers given it by goodness.
 C. S. Lewis, Mere Christianity (1952). copy citation

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Author C. S. Lewis
Source Mere Christianity
Topic goodness evil
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

“And do you now begin to see why Christianity has always said that the devil is a fallen angel? That is not a mere story for the children. It is a real recognition of the fact that evil is a parasite, not an original thing. The powers which enable evil to carry on are powers given it by goodness. All the things which enable a bad man to be effectively bad are in themselves good things—resolution, cleverness, good looks, existence itself. That is why Dualism, in a strict sense, will not work. But I freely admit that real Christianity” source