Walter Miller's Canticle For Leibowitz

Walter M. Miller, Jr.'s A Canticle for Leibowitz is a timeless story about apocalyptic cycles, conflicts and similarities between religion and science,
religious ethics and secular ethics, sin and redemption, myth and preternatural innocence.
Canticle is a very religious story about a monastery dedicated to preserving scientific knowledge from the time before nuclear war which devastated the world and reduced humanity to a pre-technological civilization. The Catholic Church and this monastery are portrayed as a bastion of civilization amidst barbarians and a light of faith amidst atheism.
Unfortunately, humanity destroys the Earth once again, but Miller ends with two beacons of hope: a starship headed for the unknown to help humanity begin again and the preternaturally innocent Rachel who portends a future for similarly innocent human beings repopulating the Earth. Thus, faith ultimately triumphs over atheism even in the midst of almost total catastrophe.