In 1 Corinthians 1:5, Paul tells the Corinthians why he is thankful:
Εὐχαριστῶ τῷ θεῷ μου πάντοτε περὶ ὑμῶν ἐπὶ τῇ χάριτι τοῦ θεοῦ τῇ δοθείσῃ ὑμῖν ἐν Χριστῷ Ἰησοῦ.
I give thanks to my God at all times concerning you for the grace of God that has been given to you in Christ Jesus.
The anonymous fourth century commentator known as “Ambrosiaster,” the author of the first surviving complete commentary on the Pauline epistles, finds great significance in the passive participle/verb in this verse (δοθείσῃ/datam est: he comments on a pre-Vulgate Latin text in the passage below) for what it tells us about how man relates to God, which is to say, how he is reconciled with him through the forgiveness of his sins:
“Gratias ago Deo meo semper pro vobis super gratia Dei, quae data est vobis in Christo Jesu.” Datam dicit gratiam a Deo in Christo Jesu, quae gratia sic data est, quia hoc constitutum est a Deo, ut qui credit in Christo, salvum sit sine opere: sola fide gratis accipit remissionem peccatorum.
“I give thanks to my God always for you for the grace of God that has been given to you in Christ Jesus.” He speaks of “grace given by God in Christ Jesus”–a grace that has been given in such a way because the following has been established by God: that he who believes in Christ is saved without work [sine opere]; by faith alone [sola fide] graciously [gratis] does he receive the remission of his sins.1
Ambrosiaster here draws out the implication of Paul’s doctrine of being saved “by faith apart from works,” alluded to by the phrase sine opere, and thus concludes that it is by “faith alone” that forgiveness is received gratis–“for free, graciously,” with gratis echoing the gratia of the verse itself: the “grace given to you” carries with it in this passage the sheer gratuity, the sheer gift, of God’s favor and forgiveness to sinners.2