The second edition of this book recently released:

Michael P. V. Barrett. Complete in Him: A Guide to Understanding and Enjoying the Gospel. 2nd ed. Grand Rapids: Reformation Heritage, 2017.

My endorsement:

Barrett correlates what the whole Bible teaches about the gospel in a way that is organized, clear, faithful, and edifying. As he says over and over, right thinking about the gospel produces right living in the gospel. The better you understand the gospel, the better you can enjoy it.