In The Inner Sanctum of Puritan Piety, J. Stephen Yuille demonstrates how the doctrine of the believer's union with Christ lies at the heart of the Puritan pursuit of godliness. He analyzes the whole corpus of Flavel's writing, showing how this mystical union is set upon the backdrop of God's covenant of redemption and established on the basis of the person and work of Jesus Christ. Chapters on the nature and acts of this union help readers gain a better understanding of what this union is, while chapters on the blessings, fruit, suffering, evidence, joy, practice, and hope associated with this union show more fully the experiential direction of Flavel's approach to theology.