This polemic critiques Cyril’s Christological teachings, emphasizing that God the Word remained unchangeable and divine, asserting that the incarnation involved the assumption of human flesh and nature without mutation or confusion of divine principles.
Theodoret defends the doctrine that Christ is one person with two distinct natures—divine and human—maintaining that the divine nature was not altered into flesh but that the human nature was united to the divine without impairment, while condemning claims of mixture or mutation as blasphemous.
He further stresses that the properties of each nature remain intact in Christ, and that the suffering and humility of the incarnate Christ do not imply any change or imperfection in the divine Word but reflect the voluntary union and human experience of the assumed flesh.