The story is about Julie Katz, the new Messiah, who is the daughter of God, and who is spontaneously conceived from a sperm bank donation by her father, Murray Katz, through "inverse parthenogenesis". Julie struggles with her messianic powers, the mind games of Satan, being hunted by fundamentalists, and the silence of her mother, God. This novel is a counter-theodicy similar to Morrow's Godhead Trilogy. In addition, Only Begotten Daughter refers to God as a female throughout the book. Inverse parthenogenesis is a baffled scientist's explanation for the existence of an entirely unexpected ovum in Murray Katz's latest sperm bank donation: unexpected because, as Murray himself admits, he does not know many women. Murray is a Jewish hermit pushing fifty, living alone in a lighthouse in Atlantic City, writing a book about human nature based on evidence gleaned from a job at the local Photomat. His closest friend is lesbianGeorgina Sparks, foster-mother to Julie. The result of these gathered abnormalities is Julie Katz, half-sister to Jesus. Well-schooled in the appropriate use of her messianic powers by her only visible parent, Julie reaches adulthood and explores life, death, Hell and the universe on the East Coast of the modern United States. She is ten years old when she meets her "mother's oldest friend", Mr. Wyvern; the plot thereafter is derived from the intervention of family, fun in the Absecon Inlet, the guiding phantom eye of an enemy, Pastor Billy Milk, his fundamentalist sheep roving Atlantic City with juice jugs of milk, and the problems posed by her extra gifts. The overarching story of the book is that of a satirical theodicy, questioning why human beings suffer from evil and pain, and exploring the ingenuity with which we combat those conditions. Julie eventually discovers that Amanda, the talking Sponge, is very likely God, and her spiritual mother. Amanda cares deeply about the planet, but lives at a distance from it, and is not able to affect the world beyond the occasional miracle.
Critical response
Fantasy scholar Michael-Anne Rubenstien writes: Rubenstien adds, Jo Walton has described it as "brilliant", commenting that it was "worthy of Hugo nomination".
