Start with high-confidence christian allegory books, then narrow by subgenre or adjacent topics.
Out of the Silent Planet
Unknown author
The Screwtape Letters
C. S. Lewis
The Great Divorce
Till We Have Faces
The Greatest Story Ever Told
Fulton Oursler
Joshua's Family
Joseph F. Girzone
Joshua and the Children
Joseph Girzone
Joshua
Easter Stories
C.S. Lewis, Leo Tolstoy
The Sphinx at Dawn
Madeleine L'Engle
The Eighth Arrow
J. Augustine Wetta
The Martyr of the Catacombs
James De Mille
Manalive
G. K. Chesterton
Lilith
George MacDonald, Jonathan St. John
At the Back of the North Wind
George Macdonald
