So you want to understand hell better? Assuming you have already read Is There Anything Good About Hell? these are my top five recommendations. I have purposefully chosen a mix of five books that will capture some of the breadth of the doctrine of eternal punishment. Some of these excel in biblical exegesis and defense of the doctrine, while others provide the foundational logic and presuppositional philosophy necessary in rightly comprehending this most sober subject. Honorable mention goes to Blanchard's Whatever Happened to Hell?
Hartman, L. B.
New York: Frank H. Revell, 1898.
This "peerless" work lays the foundation and logic of hell with breadth and persuasiveness. Hartman has the gift of rhetoric and an almost effortless grasp of scientific, religious, and philosophical literature. If you can get past the archaisms and the quantity of citations, this short work is simply phenomenal. It is now re-published with a biographical introduction and available here from Decretum Books, as well as at Amazon.
Ed. Christopher Morgan and Robert Peterson
Grand Rapids, MI: Zondervan, 2004.
The best modern book available on hell, this anthology includes incredible chapters from Albert Mohler, Douglas Moo, Daniel Block, and more. Although I slightly prefer the layout of a monograph, in theological rigour and usefulness, this volume is unsurpassed.
Robert A. Peterson
Phillipsburg, NJ: P&R Publishing, 1995.
In what is probably the best defense of the doctrine of hell in the last couple decades, Robert Peterson deals systematically and comprehensively with the relevant passages and question about eternal punishment. When I write in my introduction to Anything Good About Hell? that able men have already defended the doctrine of hell and more capably than I could, this was the preeminent book in my mind. Scriptural, solid, superb.
Icthus Publications, 2014.
Everyone knows "Sinners in the Hands of an Angry God, but "Wicked Men Useful in Their Destructions Only," and "The Justice of God in the Damnation of Sinners" perhaps answer more questions about hell. Edwards is hell's preeminent philosopher and theologian. Whether it is this volume or one of many others, these sermons stir both the heart and the mind.
Miller, William Ian.
New York: Cambridge University Press, 2006.
This entry may be surprising, as this book only barely touches on theological themes, let alone hell proper, however the largest need today in understanding hell is understanding the truths about retributive punishment. This book by scholar William Ian Miller is remarkable in its presentation of forgotten truths: the economics of punishment and how retribution is all about even-ness. Furthermore, I'm a sucker for words well-spoken, and Miller has quotables in bucket-loads. Highly recommended.