The book offers a scholarly research of the fifth century dispute between Theodore and Nestorius on the one hand, and Cyril and Cassian on the other. It raises the question of whether there was a genuine theological consensus behind the early church's pronouncements about Christ and uses the concept of grace to clarify this question.
It argues that there was a close connection between patristic writers' understanding of grace and of the person of Christ. It also suggests that the central issue of the christological controversy was whether God the Logos was himself personally present oon earth through the incarnation.
Theodore and Nestorius argued for a mediated divine presence, but Cyril and Cassian insisted that the Logos was the personal subject of Christ.