Start with high-confidence faith & inspiration books, then narrow by subgenre or adjacent topics.
Mere Christianity
Julian Rhind-Tutt, C. S. Lewis
Miracles
C. S. Lewis
The Weight of Glory
The Divine Milieu
Pierre Teilhard de Chardin
Waiting for God
Simone Weil
The C. S. Lewis Bible
C. S. Lewis, Anonymous
Your Spiritual Power
Ernest Holmes, Ernest Shurtleff Holmes
Liturgies of the Wild
Martin Shaw
The Road Less Traveled, Timeless Edition
M. Scott Peck
C. S. Lewis in America
Mark A. Noll, Kirk D Farney
The Last Romantic
Jeffrey W. Barbeau, Sarah Borden
The Way of Dante
Richard Hughes Gibson, Nicole Mazzarella
The Interior Castle
Teresa of Avila, Mirabai Starr