The nytimes has a nice interview with biologist Francis Collins ("Francis S. Collins: By the Book"). Collins is a former atheist who converted to Christian theism. His book "The Language of God" is excellent, reasoning that DNA gives us a "language" which, according to inference to the best explanation, leads us to the reality of God.
In the nytimes interview Collins shares his favorite books. Collins also reads scholarly books that oppose his Christian theism. He says: "One must dig deeply into opposing points of view in order to know whether your own position remains defensible. Iron sharpens iron." Correct. I'm thankful I was instructed to do this 40 years ago. In my own areas of study and teaching I'm constantly reading the work of scholarly atheists.
Collins is asked: What book has had the greatest impact on you? He responds:
"As an atheist evolving to agnosticism, and seeking answers to whether or not belief in God is potentially rational, my life was turned upside down 35 years ago by reading C. S. Lewis’s “Mere Christianity.”"