This book is much more profound than it appears at first glance. Irby makes an important distinction that I believe is fundamental to understanding Cumberland Presbyterian theology. He wisely recognizes that there is a difference between those biblical truths we hold with absolute certainty and those we hold with less certainty due to continuing differences among Christians on those points. So, for example, we all believe Christ died on the cross to make atonement for our sins; we hold that truth with complete certainty. But our differing theories of the atonement are still discussed and debated and are not, therefore, "indispensable." What the late Dr. Irby understood so well is that Christians require a solid foundation of certain truth on which to build their lives and witness. They also need to continue to seek--with the Spirit's guidance--a better understanding of those points on which true Christians differ. The indispensable doctrines ground our lives and witness, and the others provide the opportunity for more serious study and engagement of Scripture to enrich our understanding and to explain our own Protestant tradition, our own way of being Christian. Irby's theologian approach reflects what I love about the Cumberland theology. It's truly a theology of humility (Luther), but it's also firmly grounded in the clear and "indispensable" teaching of the Bible.