“The Story to End All Stories for Harlan Ellison’s Anthology Dangerous Visions” was originally published in Niekas in Fall 1968. It can now be found in The Eye of the Sibyl and Other Classic Stories by Philip K. Dick on p. 223.
After a hydrogen war, women have sex with animals and mutants in the zoo. An amalgamated human woman has sex with an alien woman in the zoo. The two mothers fight for the child. The human wins and eats the child, but only then learns that the child is God.
This “story” is really just a playful sketch by Dick written as an informal follow-up to “Faith of Our Fathers.” It has some thematic similarities with “Faith of Our Fathers,” in finding God as a horrifying aspect of the real world. It speaks to some other of Dick’s themes, such as posthumanism and the consequences of a nuclear war. It also seems to me that this brief story reflects a change in Dick’s writing toward stranger theological investigations. Notice that is lacks the social and political power of “Faith of Our Fathers.”