Augustine:
The spirit of grace, therefore, causes us to have faith, in order that through faith we may, on praying for it, obtain the ability to do what we are commanded.
http://www.lgmarshall.org/Augustine/augustine_willgrace.html
Catholic Catechism
153 When St. Peter confessed that Jesus is the Christ, the Son of the living God, Jesus declared to him that this revelation did not come "from flesh and blood", but from "my Father who is in heaven".24
Faith is a gift of God, a supernatural virtue infused by him. "Before this faith can be exercised, man must have the grace of God to move and assist him; he must have the interior helps of the Holy Spirit, who moves the heart and converts it to God, who opens the eyes of the mind and 'makes it easy for all to accept and believe the truth.'"25
1993 Justification establishes
cooperation between God's grace and man's freedom. On man's part it is expressed by the assent of faith to the Word of God, which invites him to conversion, and in the cooperation of charity with the prompting of the Holy Spirit who precedes and preserves his assent: