It almost does not count when Christopher Hitchens uses poems as reference points for his discussions of issues—he does it ALL the time. I know of no other journalist who so frequently refers to poetry and clearly has vast swathes of it memorized.
But he does it again in an article on Ayaan Hirsi Ali in Slate: this time with not Yeats, but Auden. And yes, it is "September 1, 1939." The line that he uses as a motif in his article is "the enlightenment driven away."
The article is one of many responding to Timothy Garton Ash and Ian Buruma, who independently wrote about Ali (see links provided by Pierre Joris).
The part that really struck me about Hitchens's argument is a passage from Ali herself:
"I left the world of faith, of genital cutting and forced marriage for the world of reason and sexual emancipation. After making this voyage I know that one of these two worlds is simply better than the other. Not for its gaudy gadgetry, but for its fundamental values."
Those who criticize Ali for the vehemence of her critique of Islam should keep this in mind.
(See also "Auslandsreise oder Flucht?" in the Neue Zürcher Zeitung: Nawal as-Saadawi has been forced to leave Egypt because of serious threats to her life. She, too, grew up in the "world of faith [and] genital cutting.")