It's not actually featured in the film "American Rapture" (which is a fictional movie), but the title "Denver" and the idea of Jesus riding into the city are both common themes in religious apocalyptic literature and culture, which the film plays on.
The film also uses several other songs, like:
* "The Devil's Got My Woman" by The White Stripes
* "Down In The Valley" by The Carter Family
* "You're So Vain" by Carly Simon
Let me know if you have any other questions!