Start with high-confidence christian fantasy books, then narrow by subgenre or adjacent topics.
The Dark Tower
C. S. Lewis
Talon of God
Wesley Snipes, Ray Norman
Merlin's Shadow
Robert Treskillard
Ruin
John Gwynne
Valor
Moonblood
Anne Elisabeth Stengl
King's Folly
Jill Williamson
King's Blood
King's War
Light of Eidon
Karen Hancock, Adam Verner
Mark of the Raven
Morgan L. Busse
Flight of the Raven
The 49th Mystic
Ted Dekker, Alyssa Bresnahan
From Darkness Won
The Circle Series 4-in-1
Ted Dekker, Rob Lamont
Sir Dalton and the Shadow Heart
Chuck Black
Devil in Green
Mark Chadbourn
Lilith
George MacDonald, Jonathan St. John
Kingdom of Deceit
Roberto Ricci, Ryan Kennard Burke
The Temple at Landfall
Jane Fletcher