Philip K. Dick
The Story to End All Stories for Harlan Ellison's Anthology Dangerous Visions
In a hydrogen war ravaged society the nubile young women go down to a futuristic zoo and have sexual intercourse with various deformed and non-human life forms in the cages. In this particular account a woman who has been patched together out of the damaged bodies of several women has intercourse with an alien female, there in the cage, and later on the woman, by means of futuristic science, conceives. The infant is born, and she and the female in the cage fight over it to see who gets it. The human young woman wins, and promptly eats the offspring, hair, teeth, toes and all. Just after she has finished she discovers that the offspring is God.