The Paris Review's interview with Kurt Vonnegut starts out with a discussion of Vonnegut's experiences as a infantry scout in during the Second World War. His experience as a prisoner of war during the firebombing of Dresden formed the basis for his 1969 novel Slaughterhouse Five - at least for the parts that weren't set in a zoo on the planet Tralfamador.
Before the war Vonnegut studied chemistry at Cornell University for several years. When he enlisted in the Army, he was transferred to the Carnegie Institute of Technology where he studied mechanical engineering. His studies were interrupted by the war.
After the war was over, Vonnegut went back to school to study anthropology as a post-grad at the University of Chicago. As he describes it, anthropology influenced his opinion of religion and his own atheism:
After the war, I went to the University of Chicago, where I was pleased to study anthropology, a science that was mostly poetry, that involved almost no math at all.
[. . .] [Anthropology] confirmed my atheism, which was the faith of my fathers anyway. Religions were exhibited and studied as the Rube Goldberg inventions I’d always thought they were. We weren’t allowed to find one culture superior to any other. We caught hell if we mentioned races much. It was highly idealistic.
Those views would influence the depiction of the fictional island dictatorship of San Lorenzo in his Hugo-winning 1963 novel Cat's Cradle. The government of San Lorenzo promotes (by prohibiting) a made-up religion to control its population.
Plus de détails et l'interview complète ici