At one time or another every Christian is called upon to defend the faith. Here are books I recommend as popular-level works on the subject of apologetics.
Top Recommendation

When I think of Christian apologetics, I tend to think of Evidence that Demands a Verdict or some of the classics of days gone by. But in this book Koukl offers a new approach and one that is well-suited to the times. He teaches the Christian to think well, to exemplify grace and to humbly lead a conversation to the truth. “We may spend hours helping someone carefully work through an issue without ever mentioning God, Jesus or the Bible. This does not mean we aren’t advancing the kingdom. It is always a step in the right direction when he help others think more carefully. If nothing else, it gives them tools to assess the bigger questions that eventually come up.” This excellent book provides tactics useful for addressing particular concerns and objections. See also the follow-up book Street Smarts.
Other Recommendations

Keller’s book is a powerful antidote to the voluminous works of today’s atheists and skeptics.

Pearcey goes to Romans 1 and shows how it explains all the world’s idolatry.

Chatraw explains why the methods of the apologist need to be different now than they were 20 or even 10 years ago.

Drawing on his experience as a cold case detective, Wallace makes a compelling case for the Christian faith.



Ideal for those in high school or college, this little book will help foster both curiosity about the world and confidence in God.
(See also my recommendations on evangelism and deconstruction & doubt.)