This book deals with the nature of spiritual life and what takes place when a person is born again. It particularly delineates the result of having a new nature and yet retaining a mortal body. The result of regeneration is that two differing natures reside in the body of the person in Christ. One is adapted to this world and is basically sinful. The new nature, or "the new man," is destined to be forever with the Lord in heaven and is righteous. There is a fierce conflict between these natures that must be understood. The new nature is to mature while at the same time doing battle with the old nature, or "old man," which cannot enter the kingdom of God. A proper understanding of this war within delivers one from the confusion, self-condemnation, and lack of insight that invariably accompany a fundamental ignorance of this matter.