During my last semester of undergraduate work, I took a class on the book of Hebrews. And as in most bible classes, we were assigned to read the book numerous times. I was never more confused in understanding the message of a biblical book than Hebrews.
Over this past summer, one of my reading goals was to read this book, entitled, "The Race Set Before Us: A Biblical Theology of Perseverance and Assurance" by Thomas Schreiner and Ardel Caneday. This book ranks among the top five books that I have ever read. This is so for several reasons.
I was introduced for the first time to the 'already, not yet' concepts of salvation. Many of the difficult passages in Hebrews and throughout the New Testament were problematic to me because I did not simply understand the future aspects of regeneration, redemption, adoption, and a myriad of other salvation concepts. Granted, I knew of the concept, but I did not understand how they fit into the entire scheme of salvation.
This book also remains among the best I have ever read because of its commitment to reading and interpreting the text for what it says. The authors honestly and carefully examine scores of important texts, demonstrating that the most correct reading is the most natural reading. As you study Hebrews, as I have, you realize that this is not the case with most interpreters. They squeeze, twist, and mutilate whole passages of Scripture in order to fit their systematic theology.
Lastly, this book has explained to me more clearly than ever before the concept of the race in the Christian life. We do not gain merely an entrance into a country club by which we are members and enjoy the benefits as we await our Savior. Rather, we have been given an entrance into a race which we must begin, run, and finish in order to inherit eternal life with God forever. The Christian life is so sweet and meaningful when we understand it as Paul meant it.

Acts 16:31 "Believe in the Lord Jesus and you will be saved."
Matthew 24:31 "He who stands firm to the end will be saved."