The study Why: 40 Days Pursuing Answers To Life’s Biggest Questions recommends the following books for answering the question, “Why Should I Believe In God in the First Place?”
God? A Debate Between A Christian And An Atheist, by William Lane Craig and Walter Sinnott-Armstrong
Thinking About God, by Gregory Ganssle
Mere Christianity, by C.S. Lewis
How Does Anyone know God Exists? Tough Questions, by Garry Poole
The Case for a Creator, by Lee Strobel
Can Man Live Without God, by Ravi Zacharias