I just got a copy of Dr. Mohler’s first book. He has written in other books and edited books, but this is his first published work. The way I understand it, the book is a plea for Christians to engage the culture.
Dr. Mohler argues for Christians to engage the culture instead of (1) retreating (like the Monks or the Mennonites); (2) adapting to the culture (like modern day liberals). His argument is simply that Christians have truth that has been revealed from God, and they should be joining in the conversations going on in the culture, trying to share this timeless truth.
After making his point about engaging the culture, Dr. Mohler then applies his method to the areas he thinks we need to engage the culture: Politics, law, war, education, philosophy (Darwinism), Abortion, and natural disasters. His point is to say that we as Christians have a very important role to play in our culture. Namely, we should be salt and light.