Both Uses

epiphany
in
The Kite Runner
(Edited)

But one day I had an epiphany.
p. 282.9 *

epiphany = sudden realization
Closing Sohrab's door, I wondered if that was how forgiveness budded, not with the fanfare of epiphany, but with pain gathering its things, packing up, and slipping away unannounced in the middle of the night.
p. 359.7

Definitions:

(1) (epiphany)
a sudden realization -- especially one of importance

James Joyce coined common use of the term from Christianity where it refers to the moment it was realized that Jesus was divine. When capitalized, "Epiphany" references that day twelve days after Christmas -- January 6th.

The term was widely used by James Joyce in his critical writings, and the stories in Joyce's Dubliners are commonly called "epiphanies."
(2) (meaning too rare to warrant focus)
Less commonly, as a proper noun Epiphany commemorates on January 6 how a star led the three wise men to baby Jesus twelve days after his birth.