Lamentations 5:21: Convert us, O Lord, to You, and we shall be converted: renew our days, as from the beginning.
ἐπίστρεψον ἡμᾶς κύριε πρὸς σέ καὶ ἐπιστραφησόμεθα καὶ ἀνακαίνισον ἡμέρας ἡμῶν καθὼς ἔμπροσθεν.
Ephesians 2:8: For by grace you are saved through faith: and that not of yourselves, for it is the gift of God.
τῇ γὰρ χάριτί ἐστε σεσῳσμένοι διὰ πίστεως: καὶ τοῦτο οὐκ ἐξ ὑμῶν, θεοῦ τὸ δῶρον.
Second Council of Orange (Denzinger 178): Canon 5 of the Second Council of Orange says,
If anyone says, that just as the increase [of faith] so also the beginning of faith and the very desire of credulity, by which we believe in Him who justifies the impious, and (by which) we arrive at the regeneration of holy baptism (is) not through the gift of grace, that is, through the inspiration of the Holy Spirit reforming our will from infidelity to faith, from impiety to piety, but is naturally in us, he is proved (to be) antagonistic to the doctrine of the Apostles, since blessed Paul says: "We trust, that he who begins a good work in us, will perfect it unto the day of Christ Jesus" [Phil. 1:6]; and the following: "It was given to you for Christ not only that you may believe in Him, but also, that you may suffer for Him" [Phil. 1:29]; and: "By grace you are made safe through faith, and this not of yourselves; for it is the gift of God" [Eph. 2:8]. For those who say that faith, by which we believe in God, is natural, declare that all those who are alien to the Church of Christ are in a measure faithful [cf. St. Augustine].Ecumenical Council of Trent (Denzinger 797):
It [the Synod] furthermore declares that in adults the beginning of that justification must be derived from the predisposing grace [can. 3] of God through Jesus Christ, that is, from his vocation, whereby without any existing merits on their part they are called, so that they who by sin were turned away from God, through His stimulating and assisting grace are disposed to convert themselves to their own justification, by freely assenting to and cooperating with the same grace [can. 4 and 5], in such wise that, while God touches the heart of man through the illumination of the Holy Spirit, man himself receiving that inspiration does not do nothing at all inasmuch as he can indeed reject it, nor on the other hand can he [can. 3] of his own free will without the grace of God move himself to justice before Him. Hence, when it is said in the Sacred Writings: "Turn ye to Me, and I will turn to you" [Zach. 1:3], we are reminded of our liberty; when we reply: "Convert us, O Lord, to Thee, and we shall be converted" [Lam. 5:21], we confess that we are anticipated by the grace of God.Notes & References