Sixth Column', also published as The Day After Tomorrow, is a Robert A. Heinlein novel based on an outline provided by the editor of Astounding Science Fiction, John W. Campbell The 1949 novel, derived from a 1941 magazine serialization, uses racial stereotypes that might be found objectionable today. Much of the story concerns the establishment of a fake religion to cover an underground rebellion against Asian occupiers of the United States. Its title contrasts the Fifth Column of traitors in the Spanish Civil War with a "sixth column" of patriots taking back their country. The novel, originally published under Heinlein's Anson Macdonald pseudonym, falls outside his Future History series.
The novel's scientific premise is that just before the United States was occupied, a researcher at a secret Army laboratory both establishes a unified field theory, and goes beyond to build devices combining electromagnetic and gravitic spectra to give near-miraculous powers. The developer and most personnel are killed by the first test of a device using the principles.
The occupier, called the "Pan-Asians", is never precisely identified, but has aspects of 1940 perceptions both of Japanese militarism and the Soviet "Red hordes". Their colonial occupation policy holds that the occupied nations will be more peaceful if they are allowed to practice indigenous religions, so the occupiers do not object when they encounter a new religion, the cult of "Mota". It spreads rapidly across the country, providing social services that are a relief to the occupier, who does not know that the food and medical treatment come from the advanced technology. The priests are United States Army officers, and the churches hide bases of the underground.
The denouement does include examples that there can be American heroes of Asian ethnicity, as well as crazy Americans of the majority.
Sixth Column and Heinlein's views on religion
Sixth Column is based on an outline provided John W. Campbell, Another Heinlein novel dealing with religion is closer to his own style; If This Goes On—", a part of his Future History, revolves around the overthrow of a cynical and corrupt priesthood of Fundamentalist Christians.