Start with high-confidence christian theology books, then narrow by subgenre or adjacent topics.
Good Taste, Bad Taste, and Christian Taste
Frank Burch Brown
Trent
John W. O'Malley, John W. O'Malley
Justification in Perspective
Bruce L. McCormack
Across the Spectrum
Gregory A. Boyd, Paul Rhodes Eddy
Willing to Believe
R. C. Sproul
Islam
Roger Allen, Shawkat M. Toorawa
Crossing the Threshold of Love
Mary Shivanandan
The Age of Reason
Thomas Paine
Mystic Christianity
William Walker Atkinson
Yogi Ramacharaka, William Walker Atkinson
