The news today about "Atomic bombs" is so horrifying one is stunned. The utter folly of these lunatic physicists to consent to do such work for war-purposes: calmly plotting the destruction of the world! Such explosives in men's hands, while their moral and intellectual status is declining, is about as useful as giving out firearms to all inmates of a gaol and then saying that you hope "this will ensure peace". But one good thing may arise out of it, I suppose, if the write-ups are not overheated: Japan ought to cave in. Well we're in God's hands. But He does not look kindly on Babel-builders.

No. 102: From a letter to his son Christopher Tolkien (9 August, 1945) - The Letters of J. R. R. Tolkien (1981)