 Although Illinois is a concept album about the U.S. state , Stevens also explored themes related to Christianity and the Bible . As a Christian , he has written and recorded music about spiritual themes throughout his career — particularly on the 2004 album Seven Swans — and prefers to talk about religious topics through song rather than directly in interviews or public statements . The song " Decatur , or , Round of Applause for Your Stepmother ! " includes the line " It 's the great I Am " — taken from the response God gave when Moses asked for his name in the Book of Exodus ( Exodus 3 : 14 ) . " Casimir Pulaski Day " describes the death of a girlfriend due to bone cancer , and the narrator questions God in the process . More abstract allusions appear in " The Man of Metropolis Steals Our Hearts " , which utilizes Superman as a Christ figure and " The Seer 's Tower " , which references the Book of Revelation and the Second Coming of Christ . Songs which were not written with an explicit theological focus — such as " John Wayne Gacy , Jr . " — also feature religious themes such as sin and redemption . 
