Clement of Alexandria

He recognises a twofold [element in faith], both the activity of him who believes, and the excellence of that which is believed according to its worth; since also righteousness is twofold, that which is out of love, and that from fear. Accordingly it is said, "The fear of the Lord is pure, remaining for ever and ever." For those that from fear turn to faith and righteousness, remain for ever. …

The Stromata Book 7 ↗

Augustine of Hippo

As for that fear that is holy, enduring forever, if it can exist in the world to come—and how else can we interpret "enduring forever"?—it will not be a fear deterring us from an evil that might befall us but a fear preserving us in a good that can never be lost. For in a state where love of possessed good is utterly unchangeable, there, if I may put it thus, fear of all evil will be perfectly at peace. …

City of God 14.9 ↗

Thomas Aquinas

"The fear." Here he sets forth certain things that are adjacent to the law, of which one is on our part, namely fear, which leads us to observe the precepts: Eccl. 12: "Fear God and keep his commandments." And he says two things about this fear. First, he says it is holy. Second, he says it endures. Now all fear is caused by love, because a man fears to lose what he loves. And therefore, as there is a twofold love, so there is a twofold fear. There is a holy fear that is caused by holy love; and an unholy fear, caused by unholy love. …

Exposition on the Psalms of David ↗

Bonaventure

Scripture enlightens a posteriori through strict judgments. For God always imposes strict judgments upon transgressions of the precepts, as in the cases of Lucifer, Adam and his wife, the depraved upon whom came the flood, the prideful who built the tower of Babel, the Chananeans and Israel. Likewise, the New Testament is full of judgments. Now, the judgment follows the act, while the command precedes it. The judgment is related to the command: if you transgress it, you shall be punished. …

Collations on the Hexaemeron, Collation 17 ↗