The books that kept me a joyful Catholic are not weighty, but are wonderful:
“Grandmother and the Priests”, “Dear and Glorious Physician”, and “Great Lion of God” all by Taylor Caldwell. The first one is a grand collection of celtic stories that will remind you of when priest were real men. The second is about St. Luke and the third is about St. Paul.
“Mr. Blue” by Myles Connolly is a wonderful old story about a modern St. Francis.
I read all these when I was in my early twenties and they have never left me.
Ahhhh, dear friend, you have just stumbled upon one of the greatest fans of Taylor Caldwell!!! My favorites include "The Listener" and most especially, "Dialogues with the Devil".