Start with high-confidence religious lives books, then narrow by subgenre or adjacent topics.
The Historical Figure of Jesus
E. P. Sanders
Inside Scientology
Janet Reitman
Seven Men and Seven Women
Eric Metaxas
A Textbook of Hadith Studies
Mohammad Hashim Kamali
Dipa Ma
Amy Schmidt, Joseph Goldstein
Rich Mullins
James Bryan Smith, Brennan Manning
Autobiography of a Yogi
Paramahansa Yogananda
