God must work in us before we can move towards him. Our hope is founded upon the reality that God first moves graciously towards us and works within us before we come to him in faith. We thus are dependent upon God’s grace from the first to the last.
According to the Bible, humanity is clearly responsible to exercise Spirit-wrought faith in Jesus. When sinners willing place their faith in Jesus, God responds by justifying the sinner for their good and his glory. However, before we talk about the necessity of man acting in faith, we should first remember that justification is by grace.
The reality of a gracious or gratuitous and merciful justification means human beings do not earn righteousness by exerting effort. Any attempt to earn God’s favor would undo grace. Interestingly enough, both Rome and the Reformers assert the mercy of God as a leading cause of justification. For Rome, the efficient cause of justification is the mercy or grace of God.  The Reformed have no quarrel in seeing justification as a grace or even admitting that grace is the efficient cause of justification. Calvin writes, “the Scripture everywhere proclaims that the efficient cause of eternal life being procured for us was the mercy of our heavenly Father.” Turretin communicates the same reality. Turretin, in defending a forensic reading of the term justification, says that “Justification is the act…of a supreme magistrate and prince…[who shows] favor to the guilty.” The phrase “showing favor” points to the merciful and gracious character of God’s justifying act. Indeed, “we cling to this foundation.” Question sixty of the Heidelberg Catechism codifies the gracious character of justification.
Q. 60: How art thou righteous before God?
A. Only by a true faith in Jesus Christ; so that, though my conscience accuse me, that I have grossly transgressed all the commandments of God, and kept none of them, and am still inclined to all evil; notwithstanding, God, without any merit of mine, but only of mere grace, grants and imputes to me the perfect satisfaction, righteousness and holiness of Christ.”
In addition, for the Reformed, grace was prior to any human act of the will. Of course, the priority of grace was not a novelty within Christian theology. Augustine believed God’s grace preceded a move of the will towards God. He makes this explicit in reference to justification in his work, The Spirit and the Letter. “Justified, then, not by the law, not by their own will, but the weakness of our will is discovered by the law, so that grace may restore the will and the restored will may fulfill the law, established neither under the law nor in need of law (italics added).” True, this does not mean Augustine had a Reformational understanding of justification sola fide. Yet, he clearly believed in the priority of grace over an act of the will. Indeed, grace must precede an act of the will that moves towards God. In this regard, Aquinas was Augustinian. Aquinas states that “The first [step] is the infusion of grace; the second, the free-will’s movement towards God; the third, the free-will’s movement towards sin; the fourth, the remission of sin.” Thus, as is clear, for an Augustinian, grace is prior to the free-will’s (liberum arbitrium) move towards God.