Lord of the World - Robert Hugh Benson

“Mr. Benson sees the world, four or five generations hence, free at last from all minor quarrels, and ranged against itself in two camps, Humanitarianism for those who believe in no divinity but that of man, Catholicism for those who believe in no divinity but that of God.”

This apocalyptic novel from the early 1900's is sometimes deemed one of the first modern dystopias. (Summary from an original London Times review and Wikipedia)