The Fathers Taught Justifying Grace
For by grace you have been saved through faith. And this is not your own doing; it is the gift of God, not a result of works, so that no one may boast.
Do not rely on your own efforts, but on the grace of Christ. ‘You are,’ says the apostle, ‘saved by grace.’ Therefore it is not a matter of arrogance here but faith when we celebrate: we are accepted! This is not pride but devotion.
St. Ambrose, On the Sacraments 5.4.19, quoted in Thomas Oden, The Justification Reader (Grand Rapids: Eerdmans, 2002), 108.
Paul says this in case the secret thought should steal upon us that ‘if we are not saved by our own works, at least we are saved by our own faith, and so in another way our salvation is of ourselves.’ Thus he added the statement that faith too is not in our own will but in God’s gift. Not that he means to take away free choice from humanity . . . but that even this very freedom of choice has God as its author, and all things are to be referred to his generosity, in that he has even allowed us to will the good.
St. Jerome, Epistle to the Ephesians cited in Galatians, Ephesians, Philippians: Ancient Christian Commentary on Scripture, Volume VIII (Downers Grove, IL: InterVarsity, 1999), 133.