Source: p 133 of 493, Letter to Christopher Tolkien 9 August 1945, #102, The Letters of JRR Tolkien
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.
I leafed through the Tower of Babel, and Genesis 11:4.6 says:
6 And the Lord said, “Indeed the people are one and they all have one language, and this is what they begin to do; now nothing that they propose to do will be withheld from them.
So I'm guessing that Tolkien opines the main goal of these Manhattan Project scientists as building as deadly a weapon as possible, to prove their superiority as the best physicists worldwide? Then accordant with Genesis 11:4.6, these scientists would hold too much power which God prevented?
I seem to be inferring that Tolkien deems this the true motive, dominating the humanitarian one of just building something to deter Japan?
Obiter dictum: I was reading JRR Tolkien's Wikipedia entry when I lighted upon this opinion of his.