They sampled phrases from a sermon by Estus Pirkle (from his 1968 LP, If Footmen Tire You, What Will Horses Do?, itself later adapted into a film of the same name). Pirkle's narrative included an imagined visit to the US under Communism where public loudspeakers constantly proclaim "Christianity is stupid!
They extracted phrases from Estus Pirkle's sermon (presented on his 1968 LP, If Footmen Tire You, What Will Horses Do?, which was later adapted into a film) where he discussed an imagined journey to the US under Communism and public loudspeakers frequently proclaimed "Christianity is foolish!