Theodoret's chief importance is as a dogmatic theologian, it having fallen to his lot to take part in the Nestorian controversy and to be the most considerable opponent of the views of Cyril and Dioscurus of Alexandria.
The issue was not unfavourable to Theodoret's cause, but melancholy enough for Theodoret himself: the council of Chalcedon condemned monophysitism, but he unhappily yielded to pressure so far as also to take part in pronouncing " anathema upon Nestorius, and upon all who call not the Holy Virgin Mother of God, and who divide the one Son into two."
Some of Theodoret's dogmatic works are no longer extant: of his five books IIEpi Evavepwirila - ecws, for example, directed against Cyril after the council of Ephesus, we now possess fragments merely.
Mopsvestia 1 Roman Catholic writers vary greatly in their estimate of Theodoret's christology and of his general orthodoxy.
On the sources of Theodoret's church history see Jeep, Quellenuntersuchungen z.