Theodoret of Cyrus: Predestination and Foreknowledge

Since, however, some formed the idea the message was recent, and despised it as later than the way of life of the Law, he necessarily teaches about it as well. Just as he chose us in him before the foundation of the world (v.4): from the beginning, before the formation of the world, he both foreknew our situation and predetermined it. He brings out also for what he chose us: to be holy and blameless before him. And how did he choose those who were not then in existence? Predestining us in love for adoption for him (vv.4-5): he foresaw us, loved us, and predetermined our calling so that we might enjoy the gift of adoption through the Incarnation of our Savior. The phrase for him refers to the Father - that is, so that we might be called his children. Then struck by the greatness of the generosity, he went on, According to the good pleasure of his will: he will this (he is saying), this pleased him. It is, in fact, customary with the divine Scripture to refer to the intention of doing a favor as good pleasure; "You were pleased, O Lord, with your land," Scripture says, and "The Lord is pleased with those who fear him," and "My soul is not pleased with anyone who shrinks back."

- Theodoret of Cyrus (around A.D. 393 to around A.D. 457), Commentary on the Letter to the Ephesians, Chapter 1, in Theodoret of Cyrus, Commentary on the Letters of St. Paul, Volume 2, pp. 33-34 (2001), Robert C. Hill translator.