This chapter resolves the problem posed in the previous chapter, namely, the Scotist objection to the instrument doctrine. It argues that of five different strategies, only one solves the problem of coherence, and it is a solution found not only in some of Aquinas’s mature statements on instrumental causality but also in the theology of Matthias Joseph Scheeben (1835-1888), who knew the intricate debates about the doctrine after Aquinas’s time and had developed a unique response to the Scotist objection. The chapter defends Scheeben’s view, known as ’extrinsic elevation’, as the way to preserve the coherence of the two claims that God alone is the cause of grace and that Christ’s humanity is an instrumental efficient cause of grace.

The introduction states the biblical premise of the book’s argument. In Scripture, God saves human beings through the actions and sufferings of Christ in the flesh. St. Thomas Aquinas developed a theological account of the Incarnation that attempts to account for the way Scripture speaks, namely, that Christ’s humanity is the instrumental cause of salvation, or as the book calls it, "the instrument doctrine." The introduction then gives an overview of the book’s argument: this doctrine best accounts for how Jesus Christ saves Christians in virtue of his humanity. It outlines the argument of the seven following chapters.

The final chapter examines the re-engagement of Western academics with theosis in the twenty-first century and explores how, through such publications as the Philokalia and The Way of a Pilgrim, the notion of theosis has reached a broad non-churchy audience.