The following books are recommended in What Is Truth?, by Paul Copan & Mark Linville
Mere Christianity, by C.S. Lewis
Can Man Live Without God, by Ravi Zacharias
Is The Bible Intolerant, by Amy Orr-Ewing
C.S. Lewis’s Case for Christ: Insights from Reason, Imagination and Faith, by Art Lindsley
Why Bother Being Good? The Place of God in the Moral Life, by John Hare
Knowing God, by J.I. Packer
