I recently read this extraordinary book, Knowledge of Angels" by Jill Paton Walsh. It's a novel, but it's also a fable, and it's beautifully written. It's a series of philosophical arguments and a succession of brilliant illuminations that leads to an inevitable and painful conclusion.
The story of the mysterious stranger who swims ashore after being swept overboard from his ship, finding himself on an island ruled by a cardinal prince, is juxtaposed with the tale of the wolf-child being cared for and tamed by a community of nuns. The stranger is faced with the demand that he identify himself as "Christian, Saracen or Jew"; the child is faced by questions about its knowledge of anything that might be recognised as God. Both stories unfold towards each other, and the fate of one character depends on the responses of the other.
In the end I was left with the question asked by Palinor, the stranger, as "he wondered ruefully why it is that those who believe most passionately in a merciful deity who are themselves most murderous and cruel." The conclusion, coming almost as an epilogue, is inevitable and disheartening. It's not a book I can readily summarise, as the fascination lies in the beauty and the logic and the innocence and the guilt - so all I can suggest is that you read it, and ponder.